[Upgraded Design] After checking all the complaints of grinding disc set, our engineer upgraded the center hole diameter to be compatible with 4" and 4 1/2" angle grinder. The grooves of the wood grinder wheel has been enlargerd to fit widely used 1.61" black flange nut. So all the parts work right out of the box. [Fit 4" or 4 1/2" angle grinders with 5/8" & 7/8" Arbor] The angle grinder attachments set includes 3 piece of wood grinding wheel (4" dia 7/8" bore), 3 piece of silver bushing(7/8" to 5/8"). Designed to be used in all standard 4" or 4 1/2" angle grinders with 5/8" as well as M10 arbor, such as Makita, Bosch, Dewalt, Black & Decker, Milwaukee, Hitachhi & more. [Cope with Different Occasions] Hundreds of aggressive teeth of the wood grinder wheel can remove paint residue and rotted wood to smooth the surface of old furnitures. More durable than hundreds of sandpapers, save energy and improve work efficiency. [Practical Woodworking Tools] With rapid polishing and grinding speed, the grinder shaping disc is great for non-metallic materials, suitable for soft and hard wood, chipboard, laminate even plastic, without worrying about kickback. Ideal for grinding, sculpting, carving, and removing small tree stumps. [Detailed User Manual] Many customers do not know how to use carving disc for angle grinder properly, which is very dangerous. Therefore, this wood grinder wheel kit comes with a detailed usage instructions, including installation, considerations maintenance and so on. If you have any technical questions, please feel free to contact us, we have professional engineers to serve you.