Description Inner diameter: 12mm Out diameter: 30mm Thickness: 10mm Material: aluminum alloy Screw: M4 Package: 1 pcs 12mm Ptical Shaft Fixed Ring Shaft Clamp Shaft Sleeve SCS12UU Limit Ring Payment: 1.payment is default payment way. 2.All the payment must be made within 7 days. Shipping It will be sent out by SpeedPAK 8--12 DAYS Before After Purchase 1.If you have any question before or after purchase, please feel free to contact us. We will reply them as soon as possible. 2.If there is any problem on order, please contact us at once. We will solve them at fastest and friendly ways. Handling Time: Normally, we would send out all the orders in 1--3 days. Packing: We have do a lot of work on packing. We would use hardborad and pearl wool to pack them.It can protect item from bending during shipping.