JGJC 2" Non-Marking Rubber Caster Wheels 4-Pack | 5/16"×1-1/2" (8×38mm) Grip Neck with Sleeve Plugs | Furniture Casters Set of 4 Heavy Duty with Brake | Smooth & Quiet Rolling, Safe for Hardwood Floor

There is supposed to be a hollow tube that goes into the hole in the leg that the caster locks into. The ring holds the tube in place.In this Amazon picture you can see the tubes along with the caster https://a.co/d/01gU3ZEM That is why the wood broke.