HD 1080P USB Door Peephole Camera - 2MP Wide Angle Smart Security Camera with Night Vision | Wireless Home Surveillance System for Apartment & House Safety (Easy Installation, Motion Detection) - Perfect for Front Door Monitoring & Vacation Home Security

After the first one of these I ordered broke during unpacking, I ordered another one. This is when I discovered this is for 20mm diameter peepholes. No peepholes have a 20mm diameter, the standard size is 10-12mm. DO NOT BUY, this WON'T WORK ON YOUR DOOR.Original Review:This product comes with NO installation instructions, which are absolutely REQUIRED!You get the product, you plug it in before installation to make sure it works (which it did for me), then you unscrew it from the base so you can put the camera in the door. Congratulation, you just broke it, and you're not going to fix it even if you have a solder gun, because there's not enough room to reach the board inside the assembly.What you SHOULD have done is this:1. Unscrew the LARGE base first. Make sure to hold the small metal base so that is not turning, otherwise turning the large base may instead turn the small base, which will break the device.2. Make sure the cable is coming straight out of the device, so you can turn the small base without turning the cable.3. Unscrew the small base.4. Move the small base along the cable (the entire cable, which is quite long), until it is off the cable.5. Thread the device into your peephole.6. Run the small base back along the cable to the threaded rod, and re-screw it in.7. Rescrew the large base in(8. Make sure the cable is not accidentally pulled when the door opens, otherwise... the device will break).You might think, "I wouldn't accidentally break the cable when unscrewing the base, that must take a lot of force". In fact, it takes almost no force. The cable is strong, but the connect to the board uses a very thin wire. This, combined with the extreme mechanical advantage of the tight threading (think of a large lever, like a carjack), means you won't even notice the difference between breaking the wire and the friction of the threading.