Type A bases suit the following optics. 
 
Can't see the one you need? Just send us an email and we'll help you out.
 
BURRIS FAST FIRE 2-3-4, EOTECH MRDS,JPOINT RMD, LEUPOLD DELTA POINT PRO, SHIELD SMS-RMS, SIG ROMEO 1-ROMEO ZERO, VORTEX VIPER-VENOM-DEFENDER, HOLOSUN HS407K-HS507K-EPS CARRY (V-3)