Now that I have seen a Bathmate, I can say, It looks like a Cheap Pornshop Pump or "TOY".
The doctor image at the top of the page was the dead giveaway.
Almost all pumps can be used in the tub, except for (obviously) electric pumps. (Unless you get a pump that's so cheap, it doesnt like water either).
Folks, if you really want to get big by the method of pumping, you need to get a Cylinder that fits your cock properly.
If it doesnt fit properly, your going to either Squeeze into it when you get hard, and not have any room to grow, OR you'll pork out at the base of your cock and have a skinny tip.
You want a good pump? OK...
Harbor Freight, They're on sale this week, and It's good for fluids, it wont break, It's got a guage:
Harbor Freight Tools - Quality Tools at the Lowest Prices
This is the SAME PUMP THAT ONLINE "SPECIALTY Penis PUMP VENDORS" USE BUT YOU"LL PAY $40-60 for it.
Leave it in your toolbox, and the girlfriend/wife will never know any different.
Plus, YOu've got the tools to bleed out your own brakes.
Get yourself a good fitted cylinder and male CTC quick connect from:
Vacutech
NW Pump Works
Vendor of your choice that actually has a chart for size, so you can match one to fit YOU!
There ya go. Robust pump for around $100.
Oh... And the connectors for Vacutech and NW pump works are the same.
They aren't proprietary either..... CTC is a sterile fluids connection company for the food and medical industry, among others. They have an online catalog, and you can also order those off of different sites for much cheaper (Generally $0.50 to 2.00us)
I used to have the exact part number, but that was a while ago, and might have changed due to revisions.
C