Glock PI3950201 G39 Gen 3 Sub-Compact 45 GAP 3.42" 6+1 Black Steel Slide Black Polymer Grip Fixed Sights. Built around the design parameters of Glock's subcompact models, the Glock 39 melds ultimate concealment size with the power and accuracy of the .45 G.A.P. cartridge. This pistol performs well with experienced or novice shooters who want perfection in a small, powerful package.