@alan20cm (and others)
Let me add from my experience.
The latex double balloon enema nozzles from medtech are first rate. The balloons are generally “smaller” than the ones from CleanStream but will seal you well if you are willing to take the time to properly seat the distal balloon in your rectum before inflating the outer balloon. Note that the latex rubber may break down over a period of time and never, ever over inflate the balloons. You may not rupture them immediately, but every balloon has a weak spot and over inflation finds it faster than just about anything else.
There are two distinct CleanStream double balloon nozzles and one is more expensive and more difficult to find than the other. From my experience, the problems/complaints about the CleanStream nozzles are mostly associated with the less expensive model.
The more expensive model is the RU710 model. It is physically longer and has high quality inflation bulbs with chrome plated valves. The nozzle (at the business end) looks very similar to its less expensive cousin. It is different, however. When this nozzle is inflated, the center tube that delivers the enema solution stays straight and does not bend as the distal (inner) balloon is inflated. The balloons are physically a little bigger than the less expensive cousin. Amazon did sell this model but it was replaced with the less expensive one. I have only found this more expensive model on E-Bay.
The less expensive model that you find on Amazon and E-Bay is a little shorter, has larger inflation bulbs that are fitted with plastic valves with a a spring-loaded deflation valve. When the internal distal balloon inflates on this one, you will notice that the nozzle will curve inside the balloon and the nozzle tip is no longer straight forward. This doesn't adversely affect the nozzle's performance. It just means that the fluted balloon section is not designed precisely to deal with the inflation of the balloon without bending. The other weakness is the plastic, spring-loaded valves. Unfortunately the inflation tubes are pretty large in diameter and replacing the bulbs with better bulbs may be difficult because you need sufficient diameter to seal the inflation arms. Where leakage occurs is somewhere between the valve stem and the valve body. This causes the balloon to deflate. I've found success in sealing this connection with Gorilla glue.
After rupturing a couple of these balloon nozzles out of carelessness or overinflation, I've gotten pretty good at keeping them a long time. I've held some pretty massive enemas a ridiculous amount of time with these nozzles; a 4.5 liter warm baking soda enema for nearly two hours and a 3.5 liter soapy/glycerin enema for more than 85 minutes. I can't hold every enema that long, but it's nice to know that it is possible. In addition to my Model-B nozzle, I always travel with one of these double balloon nozzles.