Hornady Lock-n-Load .17 to .22 Rimfire Thickness Gauge. 17-.22 Rimfire Thickness Gauge RF17 is a fast way to measure the thickness of your cartridges. The Hornady reloading tool attaches to your caliper and includes bushings for use with all .17 and .22 caliber rimfire ammo including S.L. LR Mag and HMR. Hornady recommends you wear the lanyard around your neck and attach it to the caliper to promote safety. Properly measure the thickness of all your potential .17 and .22 caliber ammunition with the Hornady Lock & Load .17 to .22 Caliber Rim Fire Bullet Thickness Gauge. Specifications for Hornady Lock and Load Reloading Thickness Gauge for .17 & .22 Rimfire: Weight: 0.18 lbs Caliber: .17 to .22 rimfire Features of Hornady Lock-n-Load .17-.22 Thick Gauge: Allows you to measure thickness of reloaded ammunition Includes bushings for .17 to .22 caliber rimfire ammo Compatible with SL LR Mag and HMR rounds Includes lanyard for additional safety Package Contents: Hornady Lock-n-Load .17 to .22 Rimfire Thickness Gauge Hornady RF17: Lock-n-Load .17 to .22 Rimfire Thickness Gauge