Tilt fuze

A tilt fuze or fuse is a device usually used in the operation of car bombs and other such detonators, relying on the force of a jerk or similar movement for the triggering of the desired explosion.
The tilt fuze is typically a home-made mercury switch. It consists of a small tube no larger than a medical tablet bottle, made from plastic, glass or some other such material. At the bottom end of the tube, a certain volume of mercury is placed, while at the cap end are wired two live electrical contacts linked to a battery and bomb. This apparatus is then fixed lengthwise to the target vehicle; most usually, the tube is attached to the underside, below the driver or passenger's seat (depending on the desired target and the strength and quantity of the detonators) or within the mudguards.