H4 Heads Up Display for Car Auto Dimming Speedometer Shows Real Time Speed Compass Direction with Switchable KM/H/MPH Units on Windshield.

This worked pretty well. I have a heads-up display on my car, so I wanted to get one for my daughter. Her speed control is not very good. She tends to drive too fast, then too slow -- not at a steady speed. I am hoping that the digital readout will make her more conscious of her speed. Since I started using a car with an integrated heads-up display, I've become much more conscious of my speed. It's easy to install. I would recommend getting a USB hub as it will use up one of the USB ports (nowadays, those are cheap and available). It only does speed measurement and it's as accurate as GPS can be, which is to say not as perfect as an integrated HUD. However, the device can be calibrated for accuracy (add or subtract a few mph, as needed). It also shows direction (North, East, South and West; when going in between, both lights are lit (e.g. both N and W when pointed northwest). The cord is unsightly, but if you saw my daughter's car, that would be the least unsightly thing you'd notice (think pizza boxes and water bottles). It was not obvious to me how to position it so that the display was perfectly straight up and down (if that matters to you) because her dashboard is curved. I found the best orientation and left it at that. It comes with a reflective rectangle, but making that match up to the display was not an obvious task and frankly the display is bright enough without it (although I have not observed it during night driving). This device is so cheap it's really a wonder why anyone would go without a heads-up display. Well, I think my fussy wife might object to the visible cord and even seeing the device on her dashboard. But for an after-market device, I find it perfectly suitable.

I was looking for a digital display when I found this. It is very user friendly and the display is perfect. Needed a compass that I could see at night. The speedometer was a plus. P

Love it!!!

Unobtrusive, good image projection, clear colorful image on windshield, cable provided is long enough to reach rear power source. Excellent accuracy. Could have better use instructions.

Great product. Very accurate!