The Spring Lock for Assembling QuietSite™ Sound Barriers on Metal Frame, 6 Pack, model 26476, is used with the 6-inch QuietSite Stacking Pins model 26472 when stacking sound panels on frames to create a safe way to hold the panel. Use the spring lock with the replacement stacking pins, in case original pins are lost or damaged during use. Sold in packs of 6.