The sphere was covered in stockinette which was coated with a liberal amount of birdlime, an extremely adhesive substance from which the nickname 'sticky bomb' was derived. A casing made out of thin sheet-metal and formed of two halves, was placed around the sphere and held in place by a wooden handle, inside which was a five-second fuse.[31] The handle also contained two pins and a lever; the first pin was pulled out to make the casing fall away and the second to activate the firing mechanism in the grenade. This primed the grenade, with the lever being held down to ensure the fuse was not triggered; then the user would run up to the tank and stick the grenade to its hull, using as much force as possible to break the sphere and spread the nitroglycerin onto the hull in a thick paste.[15] Another alternative was for the user to throw it at the tank from a distance.