I dive Worthington 120’s , on dive over 100ft, lend my buddies my extra 120. That why you should always get tanks in pairs. I also take 10lb off my weight belt, which is a big deal when diving 40 deg water. The extra air is great when diving with inxperianced divers too. I don’t worry about draining my tank with someone attached to my octo on a 100ft dive.