The Chimp Primal Bell by Onnit is a 36 pound kettle bell that is fantastic for strengthening arms and building muscle. Although I can personally only do a few reps with this weight (and only use it for those workouts that require both arms), my husband loves this for single arm lifts! Very well made, chip resistant, and a very wide handle bar that allows you to safely move the weight through a wide range of motion. Highly recommend this for serious fitness enthusiasts!