These are the best in my opinion.

Even though i haven't used other brands, Ive used these for quite a few years, and they have never failed and always hold exact pressure no matter what the conditions. And i have put them thru the test with lots of nasty water along the inland gulf coast rivers/sandbars with mud, sand, lily pads, and wood chips from rotten stumps.

They are not cheap though, esp for a plastic tee, a $2 spring, and a small rubber diaphram. Should be $50 in parts, but they are $400.

Worth every penny. Not long ago at all they were $200 or even less.

You can get aftermarket adjustable brass ones with a 1.25 SS T fitting for less than $150.

Good to know Griff

Have you had luck with any particular brand or model? If you cant send that on here, then PM me please.
I have other friends that would like some, but the Mercs are too expensive.