These are aqua science branded neoprene sweat jackets for mineral tanks that unfortunately came defective, They still work for the tanks and keep sweating off. You have to put the jacket on before installation or if you take the top of the valve head off. It unfortunately does not zip correctly, see pictures 2 and 3. We have a lot so contact us if you need bulk.
THE PICTURE SHOWN IS OF A 12X52 MINERAL TANK.