DARTMOOR SPIN BICYCLE SEATCLAMP DESCRIPTION: New lightweight and affordable seat clamp made of AL 6061-T6. Available in bolt or QR version. For 31.6 OR 30.9 Seatpost Use Lightweight and durable seat clamp made of anodized aluminum 6061-T6. Fastening by bolt clamping. Available in various diameters. Weight: approx. 20 g (manufacturer's specification) NOTE: PLEASE CHECK YOUR BICYCLE FRAME SPECIFICATION FIRST BEFOIRE ORDERING.