Would not be without a tire pressure monitor, and am very satisfied with TST. I've got the system with replaceable batteries - don't remember the model number. First tried a NVision, but it gave too many false alarms. Switched to TST and never a problem.
It has alerted me to a leaking valve stem and three slow leaks from nails. (Funny, I went for several years without picking up a nail and then I got three just last season.) Was able to stop before any damage to tires. Tires would have been run flat and ruined without tire monitor. Monitor system has definitely paid for itself.