The Reptilia Black Hole Polymer Magwell compatible with Glock pistols is molded from reinforced polymer. The Black Holes enlarged magazine well opening helps facilitate more efficient reloads without adding unnecessary bulk to your carry or duty sidearm. Compatible with 9mm/40 Glock pistols, the Black Hole utilizes a unique rear spacer to ensure seamless. This model is compatible with Glock 19 Gen3-4, Polymer 80's PF940C. *Note: It is not compatible with 10 round factory Glock magazines.