Black 3 7/8" diameter, Looks similar to our #76 but is a smaller diameter. Intended only for 1" dia Threaded Post.
All ACME threads are not the same. You will be at risk to return this product. Our Bell will properly fit our Posts SKU 81 and others.
Manual bell for use on 4 leg older office swivel chairs
Be sure to install Thrust washer first and Bell lastly.