Their main purpose is to balance a bow to provide steadier aiming. They' ve evolved into serving a dual role to include vibration reduction.

For balance, best bet is to find a pro shop that will let you try several different weight/length combos, as what works for me may not work for you, we all hold the bow a bit differently. Choose the size that best suits your style.

For vibration dampening, I don' t think you can beat the Stealth, HIGH quality and reasonably priced (around $35)