Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Colt model no. | Name | Stock | Fire control | Rear sight | Forward assist | Case deflector | Barrel length | Barrel profile | Barrel twist | Hand guards | Bayonet Lug | Muzzle device |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 601 | AR-15 | A1 | S-1-F | A1 | No | No | 20 in. | A1 | 1:14 (early) or 1:12 (late) | Triangular | Yes | Type 1 Duckbill/Type 2 Duckbill |
| 602 | AR-15 | A1 | S-1-F | A1 | No | No | 20 in. | A1 | 1:12 | Triangular | Yes | Type 2 Duckbill |
| 603 | XM16E1 | A1 | S-1-F | A1 | Yes | No | 20 in. | A1 | 1:12 | Triangular | Yes | Type 2 Duckbill |
| 603 | M16A1 | A1 | S-1-F | A1 | Yes | No | 20 in. | A1 | 1:12 | Triangular | Yes | A1 |
| 604 | M16 (No XM16 designation) | A1 | S-1-F | A1 | No | No | 20 in. | A1 | 1:12 | Triangular | Yes | A1 |
| 605 | CAR-15 Carbine | A1 | S-1-F | A1 | No | No | 15 in. | A1 | 1:12 | Triangular | No | Type 2 Duckbill |
| 605A | CAR-15 Carbine | A1 | S-1-F | A1 | Yes | No | 15 in. | A1 | 1:12 | Triangular | No | Type 2 Duckbill |
| 605B | CAR-15 Carbine | A1 | S-F-1-3 | A1 | No | No | 15 in. | A1 | 1:12 | Triangular | No | Type 2 Duckbill |
| 606 | CAR-15 Heavy Assault Rifle M1 | A1 | S-1-F | A1 | No | No | 20 in. | HBAR | 1:12 | Triangular | Yes | Type 2 Duckbill |
| 606A | CAR-15 Heavy Assault Rifle M1 | A1 | S-1-F | A1 | Yes | No | 20 in. | HBAR | 1:12 | Triangular | Yes | Type 2 Duckbill |
| 606B | CAR-15 Heavy Assault Rifle M1 | A1 | S-F-1-3 | A1 | Yes | No | 20 in. | HBAR | 1:12 | Triangular | Yes | Type 2 Duckbill |
| 607 | CAR-15 SMG | 1st Generation | S-1-F | A1 | No | No | 10 in. | A1 | 1:12 | Short Triangular | No | Type 1 and 2 Duckbill and 3.5" Moderator |
| 607A | CAR-15 SMG | 1st Generation | S-1-F | A1 | Yes | No | 10 in. | A1 | 1:12 | Short Triangular | No | Type 1 and 2 Duckbill and 3.5" Moderator |
| 607B | CAR-15 SMG | 1st Generation | S-F-1-3 | A1 | No | No | 10 in. | A1 | 1:12 | Short Triangular | No | Type 1 and 2 Duckbill and 3.5" Moderator |
| 608 | CAR-15 Survival Rifle | Tubular | S-1-F | A1 | No | No | 10 in. | A1 | 1:12 | Short Round | No | Conical or 3.5" Moderator |
| 609 | XM177E1 | 2nd Generation | S-1-F | A1 | Yes | No | 10 in. | A1 | 1:12 | Short Ribbed | No | 3.5" or 4.5" Moderator |
| 610 | XM177 or GAU-5/A | 2nd Generation | S-1-F | A1 | No | No | 10 in. | A1 | 1:12 | Short Ribbed | No | 3.5" or 4.5" Moderator |
| 610B | CAR-15 SMG | 2nd Generation | S-F-1-3 | A1 | No | No | 10 in. | A1 | 1:12 | Short Ribbed | No | 3.5" or 4.5" Moderator |
| 611 | M16 HBAR | A1 | S-1-F | A1 | Yes | No | 20 in. | HBAR | 1:12 | Triangular | Yes | A1 |
| 611P | M16 HBAR (License produced by Elisco Tools) | A1 | S-1-F | A1 | Yes | No | 20 in. | HBAR | 1:12 | Triangular | Yes | A1 |
| 613 | M16 | A1 | S-1-F | A1 | Yes | No | 20 in. | A1 | 1:12 | Triangular | Yes | A1 |
| 613P | M16 (License produced by Elisco Tools) | A1 | S-1-F | A1 | Yes | No | 20 in. | A1 | 1:12 | Triangular | Yes | A1 |
| 614 | M16 | A1 | S-1-F | A1 | No | No | 20 in. | A1 | 1:12 | Triangular | Yes | A1 |
| 615 | M16 HBAR | A1 | S-1-F | A1 | No | No | 20 in. | HBAR | 1:12 | Triangular | Yes | A1 |
| 616 | M16 HBAR | A1 | S-1-F | A1 | No | No | 20 in. | HBAR | 1:12 | Round | Yes | A1 |
| 619 | XM177E1 | 2nd Generation | S-1-F | A1 | Yes | No | 10 in. | A1 | 1:12 | Short Ribbed | No | 3.5" or 4.5" Moderator |
| 620 | CAR-15 | 2nd Generation | S-1-F | A1 | No | No | 10 in. | A1 | 1:12 | Short Ribbed | No | 3.5" or 4.5" Moderator |
| 621 | M16A1 HBAR | A1 | S-1-F | A1 | Yes | No | 20 in. | HBAR | 1:12 | Triangular | Yes | A1 |
| 629 | XM177E2 | 2nd Generation | S-1-F | A1 | Yes | No | 11.5 in. | A1 | 1:12 | Short Ribbed | No | 4.5" Moderator |
| 630 | GAU-5A/A | 2nd Generation | S-1-F | A1 | No | No | 11.5 in. | A1 | 1:12 | Short Ribbed | No | 4.5" Moderator |
| 633 | Colt SMG | 2nd Generation | S-1-F | A1 | No | Yes | 7 in. | A1 | 1:10 | Short Round | No | None |
| 634 | Colt SMG | 2nd Generation | Conflict between S-1 and S-1-F | A1 | No | Yes | 10 in. | A1 | 1:10 | Short Ribbed | No | A2 |
| 635 | Colt SMG | 2nd, 3rd, or 4th Generation | S-1-F | A1 | No | Yes | 10 in. | A1 | 1:10 | Short Ribbed | No | A2 |
| 635S | Colt SMG | 2nd Generation | S-1-F | A1 | No | Yes | 10 in. | A1 w/ integral silencer | 1:10 | Short Ribbed | No | A2 |
| 639 | XM177E2 | 2nd Generation | S-1-F | A1 | Yes | No | 11.5 in. | A1 | 1:12 | Short Ribbed | No | 4.5" Moderator or A1 |
| 639 | Colt SMG | 2nd | S-1-3 | A1 | No | Yes | 10 in. | A1 w/ integral silencer | 1:10 | Short Ribbed | No | A2 |
| 640 | XM177E2 | 2nd Generation | S-1-F | A1 | No | No | 11.5 in. | A1 | 1:12 | Short Ribbed | No | 4.5" Moderator or A1 |
| 645 | M16A1E1/M16A2 | A2 | S-1-3 | A2 | Yes | Yes | 20 in. | A2 | 1:7 | Ribbed | Yes | A2 |
| 645E | M16A2E1 | Flattop (w/ flip down front sight) | S-1-3 | A2 | Yes | Yes | 20 in. | A2 | 1:7 | Ribbed | Yes | A2 |
| 646 | M16A2E3/M16A3 | A2 | S-1-F | A2 | Yes | Yes | 20 in. | A2 | 1:7 | Ribbed | Yes | A2 |
| 649 | GAU-5A/A | 2nd Generation | S-1-F | A1 | No | No | 11.5 in. | A1 | 1:12 | Short Ribbed | No | 4.5" Moderator |
| 650 | M16A1 carbine | A1 | S-1-F | A1 | Yes | No | 14.5 in. | A1 | 1:12 | Short Ribbed | Yes | A1 |
| 651 | M16A1 carbine | A1 | S-1-F | A1 | Yes | No | 14.5 in. | A1 | 1:12 | Short Ribbed | Yes | A1 |
| 652 | M16A1 carbine | A1 | S-1-F | A1 | No | No | 14.5 in. | A1 | 1:12 | Short Ribbed | Yes | A1 |
| 653 | M16A1 carbine | 2nd Generation | S-1-F | A1 | Yes | No | 14.5 in. | A1 | 1:12 | Short Ribbed | Yes | A1 |
| 653P | M16A1 carbine (License produced by Elisco Tools) | 2nd Generation | S-1-F | A1 | Yes | No | 14.5 in. | A1 | 1:12 | Short Ribbed | Yes | A1 |
| 654 | M16A1 carbine | 2nd Generation | S-1-F | A1 | No | No | 14.5 in. | A1 | 1:12 | Short Ribbed | Yes | A1 |
| 656 | M16A1 Special Low Profile | A1 | S-1-F | Flattop | Yes | No | 20 in. | HBAR | 1:12 | Triangular | Yes | A1 |
| 701 | M16A2 | A2 | S-1-F | A2 | Yes | Yes | 20 in. | A2 | 1:7 | Ribbed | Yes | A2 |
| 702 | M16A2 | A2 | S-1-3 | A2 | Yes | Yes | 20 in. | A2 | 1:7 | Ribbed | Yes | A2 |
| 703 | M16A2 | A2 | S-1-F | A2 | Yes | Yes | 20 in. | A1 | 1:7 | Ribbed | Yes | A2 |
| 705 | M16A2 | A2 | S-1-3 | A2 | Yes | Yes | 20 in. | A2 | 1:7 | Ribbed | Yes | A2 |
| 707 | M16A2 | A2 | S-1-3 | A2 | Yes | Yes | 20 in. | A1 | 1:7 | Ribbed | Yes | A2 |
| 711 | M16A2 | A2 | S-1-F | A1 | Yes | No and Yes | 20 in. | A1 | 1:7 | Ribbed | Yes | A2 |
| 713 | M16A2 | A2 | S-1-3 | A2 | Yes | Yes | 20 in. | A2 | 1:7 | Ribbed | Yes | A2 |
| 719 | M16A2 | A2 | S-1-3 | A2 | Yes | Yes | 20 in. | A1 | 1:7 | Ribbed | Yes | A2 |
| 720 | XM4 Carbine | 3rd Generation | S-1-3 | A2 | Yes | Yes | 14.5 in. | M4 | 1:7 | Short Ribbed | Yes | A2 |
| 723 | M16A2 carbine | 3rd Generation | S-1-F | A1 | Yes | Yes | 14.5 in. | A1 | 1:7 | Short Ribbed | Yes | A1 |
| 725A | M16A2 carbine | 3rd Generation | S-1-F | A1 | Yes | Yes | 14.5 in. | A1 | 1:7 | Short Ribbed | Yes | A2 |
| 725B | M16A2 carbine | 3rd Generation | S-1-F | A1 | Yes | Yes | 14.5 in. | A2 | 1:7 | Short Ribbed | Yes | A2 |
| 726 | M16A2 carbine | 3rd Generation | S-1-F | A1 | Yes | Yes | 14.5 in. | A1 | 1:7 | Short Ribbed | Yes | A1 |
| 727 | M16A2 carbine | 3rd Generation | S-1-F | A2 | Yes | Yes | 14.5 in. | M4 | 1:7 | Short Ribbed | Yes | A2 |
| 728 | M16A2 carbine | 3rd Generation | S-1-F | A2 | Yes | Yes | 14.5 in. | M4 | 1:7 | Short Ribbed | Yes | A2 |
| 733 | M16A2 Commando / M4 Commando | 3rd or 4th Generation | S-1-F | A1 or A2 | Yes | Yes or No | 11.5 in. | A1 or A2 | 1:7 | Short Ribbed | No | A1 or A2 |
| 733A | M16A2 Commando / M4 Commando | 3rd or 4th Generation | S-1-3 | A1 or A2 | Yes | Yes or No | 11.5 in. | A1 or A2 | 1:7 | Short Ribbed | No | A1 or A2 |
| 734 | M16A2 Commando | 3rd Generation | S-1-F | A1 or A2 | Yes | Yes or No | 11.5 in. | A1 or A2 | 1:7 | Short Ribbed | No | A1 or A2 |
| 734A | M16A2 Commando | 3rd Generation | S-1-3 | A1 or A2 | Yes | Yes or No | 11.5 in. | A1 or A2 | 1:7 | Short Ribbed | No | A1 or A2 |
| 735 | M16A2 Commando / M4 Commando | 3rd or 4th Generation | S-1-3 | A1 or A2 | Yes | Yes or No | 11.5 in. | A1 or A2 | 1:7 | Short Ribbed | No | A1 or A2 |
| 737 | M16A2 | A2 | S-1-3 | A2 | Yes | Yes | 20 in. | HBAR | 1:7 | Ribbed | Yes | A2 |
| 738 | M4 Commando Enhanced | 4th Generation | S-1-3-F | A2 | Yes | Yes | 11.5 in. | A2 | 1:7 | Short Ribbed | No | A1 or A2 |
| 741 | M16A2 | A2 | S-1-F | A2 | Yes | Yes | 20 in. | HBAR | 1:7 | Ribbed | Yes | A2 |
| 742 | M16A2 (Standard w/ bipod) | A2 | S-1-F | A2 | Yes | Yes | 20 in. | HBAR | 1:7 | Ribbed | Yes | A2 |
| 745 | M16A2 (Standard w/ bipod) | A2 | S-1-3 | A2 | Yes | Yes | 20 in. | HBAR | 1:7 | Ribbed | Yes | A2 |
| 746 | M16A2 (Standard w/ bipod) | A2 | S-1-3 | A2 | Yes | Yes | 20 in. | HBAR | 1:7 | Ribbed | Yes | A2 |
| 750 | LMG (Colt/ Diemaco project) | A2 | S-F | A2 | Yes | Yes | 20 in. | HBAR | 1:7 | Square LMG | Yes | A2 |
| 777 | M4 Carbine | 4th Generation | S-1-3 | A2 | Yes | Yes | 14.5 in. | M4 | 1:7 | M4 | Yes | A2 |
| 778 | M4 Carbine Enhanced | 4th Generation | S-1-3-F | A2 | Yes | Yes | 14.5 in. | M4 | 1:7 | M4 | Yes | A2 |
| 779 | M4 Carbine | 4th Generation | S-1-F | A2 | Yes | Yes | 14.5 in. | M4 | 1:7 | M4 | Yes | A2 |
| 901 | M16A3 | A2 | S-1-F | Flattop | Yes | Yes | 20 in. | A2 | 1:7 | Ribbed | Yes | A2 |
| 905 | M16A4 | A2 | S-1-3 | Flattop | Yes | Yes | 20 in. | A2 | 1:7 | Ribbed | Yes | A2 |
| 920 | M4 Carbine | 3rd and 4th Generation | S-1-3 | Flattop | Yes | Yes | 14.5 in. | M4 | 1:7 | M4 | Yes | A2 |
| 921 | M4E1/A1 Carbine | 4th Generation | S-1-F | Flattop | Yes | Yes | 14.5 in. | M4 | 1:7 | M4 | Yes | A2 |
| 921HB | M4A1 Carbine | 4th Generation | S-1-F | Flattop | Yes | Yes | 14.5 in. | M4 HBAR | 1:7 | M4 | Yes | A2 |
| 925 | M4E2 Carbine | 3rd or 4th Generation | S-1-3 | Flattop | Yes | Yes | 14.5 in. | M4 | 1:7 | M4 | Yes | A2 |
| 927 | M4 Carbine | 4th Generation | S-1-F | Flattop | Yes | Yes | 14.5 in. | M4 | 1:7 | M4 | Yes | A2 |
| 933 | M4 Commando | 4th Generation | S-1-F | Flattop | Yes | Yes | 11.5 in. | A1 or A2 | 1:7 | Short Ribbed | No | A2 |
| 935 | M4 Commando | 4th Generation | S-1-3 | Flattop | Yes | Yes | 11.5 in. | A1 or A2 | 1:7 | Short Ribbed | No | A2 |
| 938 | M4 Commando Enhanced | 4th Generation | S-1-3-F | Flattop | Yes | Yes | 11.5 in. | A2 | 1:7 | M4 | No | A2 |
| 977 | M4 Carbine | 4th Generation | S-1-3 | Flattop | Yes | Yes | 14.5 in. | M4 | 1:7 | M4 | Yes | A2 |
| 941 | M16A3 | A2 | S-1-F | Flattop | Yes | Yes | 20 in. | HBAR | 1:7 | Ribbed | Yes | A2 |
| 942 | M16A3 (Standard w/ bipod) | A2 | S-1-F | Flattop | Yes | Yes | 20 in. | HBAR | 1:7 | Ribbed | Yes | A2 |
| 945 | M16A2E4/M16A4 | A2 | S-1-3 | Flattop | Yes | Yes | 20 in. | A2 | 1:7 | Ribbed | Yes | A2 |
| 950 | LMG (Colt/ Diemaco project) | A2 | S-F | Flattop | Yes | Yes | 20 in. | HBAR | 1:7 | Square LMG | Yes | A2 |
| "977" | M4 Carbine | 4th Generation | S-1-3 | Flattop | Yes | Yes | 14.5 in. | M4 | 1:7 | M4 | Yes | A2 |
| 978 | M4 Carbine Enhanced | 4th Generation | S-1-3-F | Flattop | Yes | Yes | 14.5 in. | M4 | 1:7 | M4 | Yes | A2 |
| 979 | M4A1 Carbine | 4th Generation | S-1-F | Flattop | Yes | Yes | 14.5 in. | M4 | 1:7 | M4 | Yes | A2 |
Question:
What's the type of muzzle devices on the models with round hand guards?
Answer:
A1