Just pushes on to a 1 or 2 liter bottle. Made with dogs in mind obviously, but sailors are filthy animals so they should like them ;)
Here is the company boilerplate:
Turn any plastic soda bottle into a portable shower!
The Mud Dog Travel Shower simply screws onto most plastic bottles to create a quick, convenient shower to clean off a playful puppy or muddy gear after a romp on the trail.
- Fits Standard PET soda bottles from 16oz to 2 liter (not included)
- Shower time is over a minute long (with 2 liter bottle)
- Made of dishwasher safe, food grade silicone.