Just to let you know, the night sights are 6.9 mm which is what comes on the G21 from the factory.
Certified Glock Armorer
G22RTF2/G G31C RTF2/G Custom
G20, G22C, G26 X2, G27, G32, G33 All Gen 3.
Ruger Security Six .357 Mag.
Ruger Super Blackhawk .44 Mag.