As you know, most of the Sonoff products are not DIN rail mounted. This makes it difficult to put the Sonoff products into the switchboard. It provides users with an easy way to install their smart switches to their switchboards. This can work with most of the Sonoff products, including Basic, RF, Pow, TH10/16, Dual, and G1. The installation is very simple. It has a blue clip, which allows you to push to fix the switch to the DIN rail or pull to take it down. You don't need any external tools. The material is fire-retardant ABS and the fire rating is V0. Included are the required screws. This fits perfectly with the original holes. In conclusion, you don't need to drill any holes.