A separate piece of material set into the club's hitting surface, most common in putters. Inserts made of soft polymer or lightweight aluminum give a softer feel and quieter sound at impact — Odyssey's White Hot insert is the classic example and has anchored their putter line for decades. The softer feel helps many players control distance on fast greens, and using a light insert lets designers move the saved weight to the perimeter for stability. Some drivers and irons use face inserts too, usually thin high-strength alloys to boost ball speed.