Type A bases suit the following optics. 
 
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C-MORE RTS2-STS2, MEOSIGHT III, MEORED, TRIJICON RMR-SRO, SIG ROMEO 3, BENTHLEY TSX6- A-1, VORTEX RAZOR, TONISYSTEM ZR-ZX-ZT, HOLOSUN HS407C-HS407CO X2- HS407C X2-HS507C-HS507 COMP-HS508T