Bought one of these a few months ago. Battery lasts weeks, small and unobtrusive, easy to set up.
Left home this morning with the rear at 42psi, got a quarter mile to work and got the flashing light and beeping alarm that the pressure was 30. Turned around, rode back to my garage and it was at 20.
Without the monitor, I would’ve got a couple of miles from home before realising it was completely flat. Well worth the money.