Remote and Proximity Damage Booster is a gear perk that raises the damage of your proximity explosives and C4. It suits a trap build where you mine roads or blow up vehicles from a distance.
Your placed explosives hit harder, so one charge is more likely to destroy a vehicle or kill a group outright.
Wear the Techmaster Pants in the legs slot. Gear perks are fixed to the piece of clothing that carries them, so you get this one by wearing that piece, not by unlocking it in a menu.
Techmaster Pocket lets you carry more of these gadgets, and Proximity Prevention on the Techmaster Boots keeps you safe from enemy mines.