Utilizing their magazine extension technology the Tyrant Designs Glock 43x & 48 magazine extension is the fastest and easiest installing mag extension ever! Adds 4 rounds to your factory magazine AND includes a 10% power spring. Drop your mags faster, and grab them easily with their machined inlay! Why do they install so quickly? Tyrant Designs use their retention plunger technology that allows the magazine extension to easily slide onto the bottom of your magazine! The entire install happens in 10 seconds or less and with no tools! Want to take it off? Easy, just push the plunger down and slide the magazine base plate off! Their magazine base pads are CNC machined from Mfg: Tyrant Cnc