50' ish you can see the bright mark at the bottom where i did a 5 gal batch, it should work perfectly for 11 gal batch in the keggel.
copper prices in the store are CRAZY osh wants +90$ for 50' of 1/2~3/8 while hd wants near 70$ (+ 10% tax) I forget how much I paid for it online but I think it was under 40$ +shipping **edit: it was 47$ just found the shipper** (which wasn't too much because i think they gave it to a meth head hitch hiking across country)
link