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 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| CR6724 | Colt Accurized Rifle | A2 | S-1 | Flattop | Yes | Yes | 24 in. | Stainless HBAR | 1:9 | FF Tube | No | None |
| MT6400 | Match Target M4 | 4th Generation | S-1 | Flattop | Yes | Yes | 16 in. | M4 | 1:7 | M4 | No | None |
| MT6400C | Match Target M4 | 4th Generation | S-1 | Flattop | Yes | Yes | 16 in. | M4 | 1:7 | M4 | No | Factory compensator |
| MT6530 | Match Target Lightweight | A2 | S-1 | A2 | Yes | Yes | 16 in. | A1 | 1:7 | Short Ribbed | No | None |
| MT6551 | Match Target Rifle | A2 | S-1 | A2 | Yes | Yes | 20 in. | A2 | 1:7 | Ribbed | No | None |
| MT6601 | Match Target HBAR | A2 | S-1 | A2 | Yes | Yes | 20 in. | HBAR | 1:7 | Ribbed | No | None |
| MT6601C | Match Target HBAR | A2 | S-1 | A2 | Yes | Yes | 20 in. | HBAR | 1:7 | Ribbed | No | Factory compensator |
| MT6700 | Match Target Competition HBAR | A2 | S-1 | Flattop | Yes | Yes | 20 in. | HBAR | 1:9 | Ribbed | No | None |
| MT6700C | Match Target Competition HBAR | A2 | S-1 | Flattop | Yes | No | 20 in. | HBAR | 1:9 | Ribbed | No | Factory compensator |
| MT6731 | Match Target Competition HBAR II | A2 | S-1 | Flattop | Yes | Yes | 16 in. | HBAR | 1:9 | Short Ribbed | No | None |
Question:
Name the barrel length for rear sight a2 for factory compensator
Answer:
20 in.