Review on LiDiVi [Upgraded Version] Dual USB Car Charger with Quick Charge 3.0, Waterproof 36W 12V USB Outlet - Fast Charging, Voltmeter & Switch for Car, Boat, Marine, ATV, Truck, and More by Will Anderson

The voltage indicator is easily visible through the rubber cover/cover. Required hole size 3cm Do you have a 3cm hole saw? Neither do I. Other youtube videos on installing USB chargers recommend step drills where I just had to stop and grab one (the discount store that rhymes with Barber Crate has an inexpensive 2 pack cheaper than buying one here). I installed it on a Vespa GTS 300 and placed it in the left knee pad (or whatever the black cap is called). I ended up using a 1" drill bit and reaming it out with a small file. I made the hole big enough so I could thread it through the hole. I figured this would help with the sealing and make sure the setup didn't vibrates.. The on/off button is easy to activate with a press of a button, no need to press it.The wire ends are spade terminals, but I cut them off for my setup and used swivel (18-22 gauge) taps instead.I got it Rated 5 stars but that's actually more like 4.85 stars for me 4.85 > 4 so I went with 5 Spare glass fuse is included.