Searching for Hardware

I'm desperately seeking hardware for a set of stilts I'm making.  I *need* certain weight grades, etc and am having trouble finding anywhere (online or in the real world) that gives me sufficient information on their products to be sure that what I'm purchasing won't let me down at a crucial moment, like when I'm surrounded by kids and might injure myself or them if I fall.

I have looked on several websites (like McMaster-carr) and just can't find the info I need.  Any recommendations would be greatly appreciated.  Thanks!