Lightweight, aluminum gauge measures length of pull, drop at comb and heel, and angle of pitch to give a precise fit. Units of measurement are in bold, easy-to-read numbers in both inches and metric for world-wide use. Measures length of pull to 24" and has an overall length of 29.5". With a length of 28", you can accurately measure drop. Optional 23" Magnetic Extension "glues" the Shotgun Combo Gauge to the rib or barrel using a magnet for hands-free operation. Extension adds 20" to steady the tool for easy drop measurement. Plastic protractor measures 180 degrees of pitch. Mfg: Robert Louis Company SPECS: Shotgun Combo Gauge - Aluminum. Overall length 28" (71cm) Magnetic Extension Aluminum. Overall length 23" (58.5cm).