Any fastener supplier will have these, for example:
https://www.gwr-fasteners.co.uk/m6-x-20mm-socket-cap-head-screws---high-tensile-129-zinc-plated-70542-p.asp
https://www.gwr-fasteners.co.uk/m6-x-25mm-socket-cap-head-screws---high-tensile-129-zinc-plated-70543-p.asp
I've bought from them in small quantities before, no problem. But there are hundreds of online fastener factors.
thank you! "fastner supplier" was the term needed - google has just been showing me large hardwear stores or trade sites!
@Maj started
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Any fastener supplier will have these, for example:
https://www.gwr-fasteners.co.uk/m6-x-20mm-socket-cap-head-screws---high-tensile-129-zinc-plated-70542-p.asp
https://www.gwr-fasteners.co.uk/m6-x-25mm-socket-cap-head-screws---high-tensile-129-zinc-plated-70543-p.asp
I've bought from them in small quantities before, no problem. But there are hundreds of online fastener factors.