These do the job well. The original metal collars kept loosening, disturbing my workout. I've used these to form a locking nut with the originals still in place. They are also perfectly suitable to use on their own and do not loosen as easily as metal ones do. They appear to be well-made and very robust. They were a perfect fit for my dumbell set.

I have got several barbells that take screw collars - but so far I have only used metal screw collars.These red ones stand out because of their colour but being plastic they feel a bit flimsy compared to my other collars.The thread feels very loose in the first couple of turns but then tightens up nicely on the weight plates.The advantage of these plastic ones over my metal ones is that they dont have any rough edges, they are definitely smoother to the touch - if that matters to you.Also they dont need an extra cushion or O ring between the collar and the plate because these wont scratch due to plastic being a softer material than iron.So far I have found they go on and come off easy enough no problem - and I do like the red colour.