Review on Highly Accurate 85MM Boat GPS Speedometer: Waterproof Marine Speed Odometer with Red Backlight, Universally Compatible for Marine Boat Car Truck 9-32V by Jeffrey Gallagher

I bought this unit because of the design and the low rpm range it offered. It is installed on a diesel locomotive and operates from a 32 V DC network. Zero to 35 mph is perfect for our application as our speed limit is 15 mph. Most other brands only had ranges of 0 to 80 mph, 0 to 120 mph, or 0 to 160 mph. I extended the receiver's antenna up to the top of the loco to keep metal objects out of the way of the receiver. The device shows speed surprisingly well considering that a significant portion of our railroad runs through the treetops. In open areas I expected the device to display correctly and it did. As we entered the tree area I expected the GPS signal to drop and the unit to hang as instructed when the GPS signal is lost. It didn't let me down and the trees are very dense with branches and leaves. Maybe he has more problems when the leaves of the tree are wet. We're only on day two, but so far so good. Bad note: If you don't leave the device on all the time, the odometer will reset to zero. Luckily one of my engineers couldn't see the red light and asked if it could be changed to blue. I made a simple change and expected the device to revert to the default red backlight after powering off. When turned on, it reverted to a blue backlight. If the device continues to work as well these two days, I'll be very glad I bought it. Edit, after the second day of operation, only the reset of the odometer appears when switched off. The odometer has saved the kilometers driven since yesterday. Guilty.