In trying to figure out how long to make my arrows several people say I need to get the correct arrow spine to determine the proper length. What is arrow spine and how do I determine it?

Arrow spine is the strength or stiffness of your shaft in relation to length, weight, size, and lbs you shoot. Which results in how much or too little flex your arrow has upon release. Unproper spine leads to bad arrow flight, especially when shooting broadheads, and long distances. Refer to Easton tuning guide www.eastonarchery.com go to the tech part.