I've run this one
Amazon.com for a year.
Plusses:
-Cheap
-Solar powered head, mounts perfectly on the headstock nut
-One of the very few I found for trikes
-Dedicated hardware, if my phone fails or the app crashes or whatev, but that is a personal preference
Minuses:
-Remove a TPMS sensor (or lose one) and ride on, you get no notification of lost signal, the PSI just locks at the last number
-Finish on the head unit has started to delaminate a bit, but my bike lives in the elements, not in a garage, so YMMV
-Beeper is not loud enough for me to hear at highway speed with earplugs in
Still, last summer it gave me enough notice to get the hell off the highway and to a gas station so I could wait for a tow truck in the shade. Worth every penny.