Adds 5 rounds to Springfield Echelon; Unique easy access floor plate design to service or clean the magazine body without the need to remove the magazine extension from the magazine body; Index cuts on the extension body to increase grip when coming out of a magazine pouch; Machined from billet 6061 aluminum; USPSA compliant (141.25 mm); Type 2 anodized; Does not require a new spring; Fits OEM Springfield Echelon magazines only; Proudly made in the USA