The 12 round magazine ships with an additional base plate to be compatible with the P365 and the P365XL
The extended 15-round magazine is compatible with all models of the SIG SAUER P365 micro-compact, concealed carry pistol. This magazine is compatible with the P365 and the P365 XL.
Sig P365 Magazine SPECS
CALIBER: 9mm Luger
MAGAZINE CAPACITY: 10 rounds, 10 rounds extended,12 rounds or 15 rounds