The Pet Life ® 'Tutor-Sheild' Martingale Safety and Training Adjustable Chain Dog Collar is composed of Durable Nylon with a Metal matingale chain designed specifically for training and behavioral correction such as biting or barking. The Nylon collar features interlock weaved stitching for further added durability. The collar features Quick-Click connecting buckles for easy on and off access. Available in Multiple Sizes and Colors. Sizing Guide (INCHES) COLLAR DIMENSIONS - SMALL - WIDTH - 0.59" NECK GIRTH - 13.38" - 15.74" (Less than 33 LBS) LARGE - WIDTH - 0.98" NECK GIRTH - 15.74" - 20.47" (Less than 99 LBS)