:campfire:I put the amp on my trailer battery mounted on the tongue (alligator clips to battery, double sided tape on the amp).
Wife and I took a 120 mile trip with her pulling the boat.
The travel trailer sensors never lost contact. I would have intermittent contact with the boat at around 75 yards, then it would stay solid when we were around 50 yards or so.
I towed the boat without the amp and never lost contact with the sensors.
I purchased through Amazon. Same price as the manu, but I like Amazon't return policy and it is easier to keep records if I have a warranty issue.
Price for additional sensors is cheaper on Amazon, BUT
The manu web site has any of the little parts (like o-rings) that you could need.
https://tsttruck.com/

I never cared about a TPMS till I blew a tire on a trip, and I didn't notice it until another driver signaled me.

I was going to go cheap on the TPMS until I started shopping for it and reading the reviews. Good range, batteries supposed to last a year or two? I take them off when I get home to save the battery (except for the boat that I use more).
The one on the link seemed to be the best on within reason. Reviews and promo said rang up to 300', I think, when using the amplifier. TST recommends using the amp (it comes in the kit).