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-LULA fit wider-body single-stack .22 LR mags with a projecting side-button. X12 is the locking loader; T12 is non-locking. They fit Walther P22/G22, Ruger SR-22, Colt 1911 .22*, S&W M&P .22*, Walther PPK/S .22 (only the T12-LULA™). *Can also use the BabyUpLULA™