The H-1ME was small, and could fit into the storage space of a standard toolbox. It could also be disassembled to fit into smaller storage spaces. The droid had multiple legs with magnetic feet which allowed it to stick to the hull of the ship it was working on. An H-1ME mechanic droid cost 10,565 credits when new.
The H-1ME was designed for spacers who couldn't afford a full-fledged astromech or were piloting ships that could not be equipped with a standard astromech. It was basically considered a toolbox that could use itself.
A mercenary flight group known as Mazer's Mynocks were known to disassemble their H-1MEs and pack them in a concussion missile housing. They would then fire these missiles at friendly damaged spacecraft. The H-1ME inside would reassemble itself and be ready to start repairs immediately when it got close to the target.