Must be good for something?

This is a cutaway sail track from a kenyon e section boom. Its what’s left over when I make T10 boom sleeves.

I keep looking at these thinking they must be good for _something_, but I have no idea what. Its got a bolt rope groove, and a neat shape… but I’m stumped. What do you think its good for?
Best response wins… a cutaway e section boom sail track!