Abstract: A modified thread design for use with a bottle and child resistant closure combination is described. The thread varies in thickness from the first end of the thread to the second end, but the thread pitch remains constant as the thread thickness varies. The modified thread design affects the rate at which the closure rises or falls along the bottle neck, and in a preferred embodiment, the thicknesses of the thread and the thread pitch are selected to allow the closure to rise at a rate that allows cap lugs on the closure to clear bottle lugs on the neck with no more than one revolution of the closure, and falls at a rate that allows the safety features to be engaged when the cap lugs pass over the bottle lugs one time.

Abstract: A safety closure including a top wall, a side wall depending from the top wall, and a locking tab projecting outwardly from the side wall, the locking tab having a reinforced end integrally connected to the side wall and a free end connected to the side wall by a biasing strap, wherein the reinforced end of the locking tab inhibits movement of the free end of the locking tab in at least an upward direction.