McMaster-Carr lists that as a "closed body turnbuckle". But they don't have anything exactly like that. The way that one is made it looks like some sort of bling on some consumer grade device. I say bling because they bothered to shine it up and maybe plate it but they couldn't be arsed to put a decent knurl on it or remove the tooling marks on the main body. It does not look like an off-the-shelf part. If that device is something that you are making (or having made) I would try and rethink the design a bit. Turnbuckles work well in tension. Look at standing rigging on a sailboat, screen doors, tie downs on trucking, etc... They do not work all that well in compression.