SD card
Comparison

Bus interface
Bus logo
Bus speed
Duplex
Card types
Card types
Card types
Card types
Spec version
Bus interface
Bus logo
Bus speed
Duplex
SD
SDHC
SDXC
SDUC
Spec version
Default Speed
N/A
12.5 MB/s
-
Yes
Yes
Yes
Yes
1.01
High Speed
N/A
25 MB/s
-
Yes
Yes
Yes
Yes
2.00
UHS-I
-
50 MB/s
Half, Full
No
Yes
Yes
Yes
3.01
UHS-I
-
104 MB/s
Half
No
Yes
Yes
Yes
3.01
UHS-II
-
156 MB/s
Full
No
Yes
Yes
Yes
4.00
UHS-II
-
312 MB/s
Half
No
Yes
Yes
Yes
4.00
UHS-III
-
312 MB/s
Full
No
Yes
Yes
Yes
6.0
UHS-III
-
624 MB/s
Full
No
Yes
Yes
Yes
6.0
SD Express
-
985 MB/s
Full
No
Yes
Yes
Yes
7.0

Question: What other duplex was it for?
Answer: Version 3.01 introduced the SDHC and SDXC cards, with speeds of 50 MB/s and 104 MB/s, for UHS-I bus.