Where IS that size Allen wrench?

I've owned several sets of Allen wrenches which I need to do repairs on my wheelchair. Every time I buy a set, I wind up losing a few of them.

In fact when my footplate dropped too low on my ski trip (yeah yeah I shouldn't have chased that snowmobile down the logging trail), I didn't have the size Allen wrench I needed with me to fix it , although there were actually people with hands that worked around. Darn. Hate that as a quad.

So this time I bought a set at sportaid.com which comes attached to a main center. $5.99. It's a bargain.