Based on my observations these plastic caster socket inserts have greatly improved our workrooms' mobility... The inserts easily fit into the legs of our work tables and chairs, allowing us to swiftly move around and rearrange our workspace as needed. The inserts are also sturdy and durable, despite being made of plastic. The only downside is that they are only compatible with certain types of casters. Overall, I highly recommend these inserts for anyone looking to enhance their industrial and scientific material handling products..