Minimize driving distractions and increase protection for both you and your dog. Bergan"s harnesses meet V9DT B2009.1. Pet Safety Durability Test (see www.v9dt.com). The minimum durability thresholds are designed to ensure confidence that a harness will withstand forces generated from sudden stops while minimizing distractions from traveling pets. The complete harness system comes equipped with adjustable safety tether and two high-grade aluminum carabiners. The harness is durable but lightweight and comfortable. Comes in 4 fully-adjustable sizes: Extra Large: for pets 80-150 lbs, neck size 16" - 23", chest size 20" - 46" . Large: for pets 50-80 lbs. Medium: for pets 25-50 lbs, neck size 9" - 35", chest size 10" - 39". Small: for pets 10-25 lbs.