1. Metal construction, thickened collar. 2. Three locking screws with protective head to prevent scratches, Adopt thicker m6 screws/locking screws with protection head to prevent scratches when fixing. 3. Guide star ring contact with the base, for the plane, to avoid contact with the base after sliding, shaking, connecting more stable. 4. The width of the playing loop is widened by 14 MM, the contact is more stable, and the thickened ring is not easy to be deformed. 5. These guide rings are made with high mechanical precision (built with CNC machines from aluminum block) and specially designed to enable you to easily install other mechanical elements such as support rings, plates or dovetail clamps. Colour:Black Material:aluminium alloy Size:130mm Package Contents: 1 x Guide Ring Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.