Not kit but I suppose it is a product.
This is the one based in Leicester. I have been before , about 4 yrs ago, and to be fair did nothing with the outcome.
So booked an hour, not sure what the range of prices are, but booked it off peak (ahem, another thread explains how I can do that, cough ) and it was £69. This included the hour session and the DVD of my swim and commentary.
It is basically a garage with the pool in, shower and changing area and a bank of video screens. So meet the coach, nice young lad, explain my needs, ie I just want to be average, and what i think some of the issues I need to work on are. I though what i needed was better body position and help with bilateral breathing. Get in, takes a bit of getting used to swimming against the jet so you aren't going to fast and come against the wall or drift back. After the warm up the coach points out a number of things, body position looks generally fine, head position too low, causing over rotation, this coupled with no bilateral breathing means rotation to other side is insufficient. (surprisingly enough when in open water I can't swim in a straight line!!) we then spend the next hour with me doing a bit of swimming and him pointing out various things. Elbows not hgh enough, entry into water, breathing etc. he points out loads of things to work on in drills. Well worth the money for me.
Is it for everyone? I would say that it depends on how badly you want to improve , it's not cheap -travel and fee means you must really want to improve tp pay it. The other thing is that much of what he pointed out was above the surface stuff, ie if you have someone who knows what they are talking about who can watch you, then they can do what he did for me. (albeit not as impactively with the video and the under the water bt is harder).
I will be drilling and going back in a couple of months.