They have the 21” and 15” water bags in gym I train at. The 21” is too heavy for me; I am 160lb.
The 15” bag is much better to work out on. The size is just better imo.
They are a nice addition to use, but not a bag to really work out on, simply because you don’t throw proper body punches on it.
And the rubber outside would perish fairly quick too I’d guess … and they very slippery when wet!
I’d suggest just go to your local amateur boxing gym. Mines open 3 times a week – I pay £3 a week.
Outdoor bags need a big hanger to ensure bag is hanging well away from wall to give you space to move around plus not rub against wall.