they didnt have an fx-5 in stock at the local store so we tried a 3 and a 4 on a 430 EXII. the 3 was too big but the 4 fits perfect so thats the one i picked up.
I thought i was going to be able to reach out to 3 or 400 feet. boy was i wrong lol. it works great , just not as far as i thought it would. i tried it out to 200 feet and it seems to still work but i know that is really pushing it.