I've never used a motor specific hour meter (and I won't rig a skiff without one...). As noted above, if possible, wire it so that it's reading only when the motor is running... My last install operated whenever the key switch was on so if you forgot and left the switch on it would read a few extra "false hours". Nowadays motors come with an internal hour meter so your tech can tell at a glance what the hours are. It's very handy though for you to be able to tell at a glance what the operating hours are for maintenance and other purposes.
You also get to choose where to mount that gauge - on the surface of your control station or inside strapped to the wiring harness (but where it's easily visible when you know where to look...).
This one is really simple and works well. Helps to track maintenance schedules when you don’t have a command link gauge or have your plotter NEMA’d to engine data. Basically it wraps around one of the plug wires and stays under your cowling.
If you have somewhat modern electronics on your skiff that are NMEA 2000 capable, buy the NMEA 2000 interface cable and plug it into your gps chartplotter. You can get engine hours directly from the engine ECM, fuel burn, along with way more other info than you can use. If not, get the Yamaha digital multifunction gauge.