Tyrant CNC Magazine Extension, Fits Springfield Echelon, +5 Rounds, Anodized Finish, Black TD-ECHEMAGEX17-BLK The Tyrant CNC Magazine Extension, also known as base pads, is designed to increase the ammunition capacity of Springfield Armory Echelon's 15 and 17-round magazines by an additional 5 rounds of 9mm. This upgrade is essential for users looking for more capacity without sacrificing the firearm's reliability and performance.