How to choose stone protectant

1. Don't just look at whether the product is optional.

2. When selecting the product, do not be easily blinded by the surface water-repellent effect of the product. The surface effect is only

What is a DVR digital video recorder

What is a DVR digital video recorder DVR (Digital Video Recorder) is a digital video recorder, which has two characteristics of digitization and video recording in terms of name. Therefore,