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I have had a couple of those cheaper ones break on me. Both no name ones eBay and origin 8 ones from eBay as well. I've found that the best ones are NJS chain tugs. They look the part and seem pretty sturdy for their low weight.
EDIT:
@Prz i have not been impressed with this type:
I have had the threads pull twice. But I might have been a bit clumsy. Overtightening shouldn't be a problem with chain tensioning.
I am currently using this but modified to fit my dropouts:
https://www.ebay.co.uk/itm/MKS-Track-Chain-Tensioners-for-10-mm-Axle-NJS-chain-Tugs-CA-MKS/233725956381?epid=1723122714&hash=item366b27111d:g:9CcAAOSwTDVfZryR
I remember looking at there's lots of cheaper variations. Ebay stuff like "chain tug" "chain tensioner"?