This is the KRISS MagEx 25+ Rd Glock 21 magazine in .45 ACP.
It features a factory Glock 21 magazine fitted with the Kriss 25 round extension. Much more reliable than the aftermarket Korean ones. KRISS produce these for their Vector SMGs which use Glock magazines.
Fits the Glock 21 as well as the Southern Gun Company Lever Release .45 ACP, with easy drop free reliability.
The original Glock magazine spring and locking plate is included if you want to convert it back at any point.
We recommend the thumb saving Maglula pistol magazine loader for use with the strong springs on Glock mags.