Select the arrows that best match the weight of your bow at your draw length. See Spine Chart for reference.

Adult arrows start at the III spine level (equivalent of 30-35#) and range in 5 lb increments up to VII spine (70-75#) 

*spine weights are designed to match the weight of "horsebows" or self bows.  If you plan to use these arrows with a standard recurve, longbow or other center-fire bow, consider a spine weight that is 5-10 lbs heavier.