It depends on what you mean.
In the pre-1950s, there were good sit-upon bags made by Tryell, the original JBL, in at least two versions.
The early ones were a rectangular shape and came in the wooden boxes with the star logo, often seen on eBay. The powdered "tonic" came in a smaller wooden box. There was a tggle fir holding the hose inside the lid. This bag held about 3 quarts
The later ones came in a somewhat larger cardboard box, blue-green in color with a mottled finish. There was a larger, square tin container of the tonic. BTW, an analysis of the tonic powder can be found on-line. The later version was not rectangular, but kidney shaped. This bag was larger and held about 5 quarts.
Both versions of the original bag were made in pieces out of rubber covered cloth, sewn and sealed together. What sometimes happens is the cloth inside rots, or the sewn seams burst.
Both the original designs have a stopcock style valve built into the nozzle base with the control extended so you can reach between your legs and turn the flow on or off and adjust it. Note there is no check valve so if you lift your weight off the bag, poopy water can and will flow backwards. For this reason, when you are done filling, urn off the tap before getting up.
The nozzles on the original are shaped like the nozzles that commonly come with a Fountain Syringe, but instead of a single hole on the end, which can become clogged with poo, have 6 rows of tiny holes. This is also claimed to produce a gentler flow.
In general, the original JBLs are well designed and will easily give mighty, colon clearing enemas without discomfort. Personally, I can take far more water with a JBL than otherwise.
They can also be used for punishment games, if that's your thing.
In contrast, the later knock-offs were poorly made. The rubber is not cloth reinforced and they tend to leak around the neck. The nozzles have no valves, although I've been told a valved version was available, and had a single hole. Not a fan.
They did occasionally show up on eBay although now seem rare.
If you can get an original, they can be used to take wonderful enemas. And, I am not interested in selling any. If there are single ladies interested in a "test drive", something might be arranged. LoL.