ZEV Technologies Citadel RMR Long Black DLC 17-4 Stainless Steel for Glock 19 Gen3 ZEV Technologies introduces a new level of modularity to the Gen3 G19 platform with Citadel Conversion Slides. Just as the name implies, you can now quickly and easily convert your Gen3 G19 for different uses. Offered in two sizes, 19L and 19XL, the longer Citadel Conversion Slides bring increased accuracy and control to the compact platform.The G19 is a great platform configured for concealed carry.