Listed is a new, Norton 07660789275 Depressed Center Adapter Kit
This reusable adapter kit contains everything you need to mound depressed center wheels and saucers with 7/8" center holes on to portable right angle or vertical shaft grinders. Adapter hubs are threaded for mounting on to standard 5/8-11 NCRH Spindles.
* For 7" or 9" Type 27 and 28 Grinding wheels 1/8" - 3/8" thick without Dis-Card Mounts
1-Flange Nut 5/8-11 NCRH
1-Socket Hex Key 3/8"