PETZL - Absorbent Foam Helmets, ALVEO COMPATIBILITY: These foam inserts are compatible with Petzl's VERTEX and ALVEO helmets. ABSORBING: This foam absorbs perspiration, helping to keep you comfortable. WASHABLE: These foam pads are machine washable. LIGHTWEIGHT: Weighing in at only 15 grams, these pads won't add bulk to your helmet. FREQUENT USE: These absorbent foam pads need regular washing for best performance.