The FuseBox RTA1001002S is Type A 100A 100mA Time Delayed Double Pole RCD
Suitable for use in FuseBox consumer units. 
The primary function of time-delayed RCD is to provide protection against electrical fire. They are most commonly used in commercial and industrial installations where the main concern isnt electric shock but rather the risk of fire.
Key Features
100A 100mA RCD
Time Delayed
Type S
Double Pole (2P)
DIN rail mount