Now available for Generation 4 G20, G21 and G41 large frame Glock handguns. The Gen 4 magwell will not fit the Gen 1-2-3 models. A new design is now available for the GEN 4 receivers. Order Gen 4 model for "new" G41. Increase the speed of your magazine reloads with a larger "Big Mouth" to funnel the magazine into your large frame Glock. These magwells are made of top quality aircraft aluminum. Each magwell includes a brass insert to add additional weight to your Glock's receiver. The addition of the 3.7 oz of additional weight will help you tame the recoil. No modifications needed to install on your Glock. Excellent for use in IPSC, GSSF Unlimited and Steel Shooting.