Small pistol grip style power screwdriver that is SHORT in both dimensions. A tool holder like a 1/4" drive impact you see at a big box store would be best for tool fitting. LONG battery life (prefer LI-on, not Nicad or NmHD), and easily and quickly charged... changeable battery.
Does that help...
GA-HVAC-Tech
Your comfort, Your way, Everyday!
GA's basic rules of home heating and AC upgrades:
*Installation is more important than the brand of equipment
*The duct system keeps the house comfortable; the equipment only heats and cools (and dehumidifies)
*The value of comfort, over the long term; leave economic choices behind!
Choose your contractor wisely!