Fragile.
Able to break or be broken.
Something that is (easily) breakable.
A set of customized hardware that is part of a drum kit. Breakables typically consist of: the drummer's cymbals including high-hats, the snare drum, the kick pedal and the drummer's stool.
Not effective.
Not able to assume active duty.
A member of the military who is unable to assume active duty.