SeeAll Night Pistol Sights use a dovetail to mount to pistols. You receive one when you purchase your SeeAll Night Pistol Sight. You can purchase another, or one for a different gun here.
Glock - fits all Glocks.
Smith & Wesson - fits M&P models (Excluding M&P Core).
Springfield XD - fits XD, XDS, XDM, XD mod 2.
FN - fits FNX FNS.
Sig - fits P Series.