The X10-LULA and V10-LULA are loaders for narrow-body, single-stack .22 LR magazines with a projecting side-button. The V10-LULA spring-loaded loader locks the mag's button anywhere you want along the mag; then just drop rounds in. Once locked on the magazine, there is no need to hold the loader. The X10-LULA is a non-locking loader. Just slide it along the mag to compress the side-button as you drop rounds in. Easy loading without any thumb pain! X10/V10 fit the following mags: Ruger Mark I/II/III & 22/45, S&W 22A/22S, Browning Buck Mark & Challenger, Beretta U22 NEOS, Colt Woodsman & Cadet, and High Standard .22s. X12-LULA/T12-L Mfg: Maglula Ltd.