You can buy cheaper inner tubes but don’t, Schwalbe (and continental) do the best tube, they are durable, let less air out and have the best smell.

You might have a Woods (DV) valve on your UA, thats ok, but we recommend that if you are going to replace your tube go for a SV (possibly a AV) as the replacement. 20 inch on the front, 26 inch on the rear. (also take a look at Airplus..holds more air in, more durable)