This loader will handle a variety of cartridges including 9mm and 40S&W. Just place the magazine into the loader, then drop in each round. As fast as you can, push down and drop in the next round.  Your magazine will be loaded in no time or effort. 
*This product is compatible with Glock magazines only.
DISCLAIMER: This product is not manufactured, authorized, endorsed, or warranted by GLOCK. GLOCK does not warrant or represent that this product is compatible with GLOCK pistols.