So I contacted Peak Design and PolarPro about the same problem...

I recently inherited two camera strap clips from a friend: a Peak Design Capture and a PolarPro Traverse. Unfortunately, he didn't save the longer hex screws for the Capture and had switched the Traverse to the shorter thumb screws to fit on his thin backpack strap without sticking out, and my thick straps definitely needed the longest screws available.

So, my idea was that of course these screws aren't custom size, they have to be US standard imperial or metric size and all I need to do is ask each company which size screws they use so I can just pick them up on the cheap at my local HD or Lowes, or if not, perhaps I can just buy couple from them?

Peak Design:

• I clicked the support page and found the chat button.
• No wait on chat... I asked my question and was told they are M8
• "But wait a sec... we can just mail you some, here, use these code to order them for free" (I am paraphrasing.)
• Order placed while I am still on chat and I profusely thank the rep for his help!

PolarPro:

• Support page has 3 options...
• #1 Chat: The chat button didn't work; I tried multiple browsers and no luck.
• #2 Email: I email and got a canned response that tickets are responded to "within 12 hours"... but I don't hear back until around the 36 hour mark, basically get told that the Traverse fits all size straps ("1-15mm thick") and they kinda ignore my question about either getting the size of the screws or if I can buy a pair from them.
• #3 Phone: I call (3 times!) and give up after being on hold for up to 20 minutes without anyone picking up...

To me, both of these manufacturers / direct retailers make high quality but very expensive stuff. I do own a couple of PolarPro filters, one of which is more expensive than my 50mm lens! I don't own any Peak Design gear, because I have also thought that their accessory stuff is just too expensive for me. In either case, I don't think it's much to expect a decent level of support... but one company far exceeded my expectations and the other just disappointed me.

Just sharing my experience. Thanks for reading!