This type of screw is often referred to as a “bolt”. Machine screws range in size, length, color, head, and usage. Generally speaking, machine screws screw into threaded sleeves (inserts), or barrel nuts buried within the wood. Products America supplies a wide variety of machine screws and can help you determine which one would best meet your needs for a crib, cradle, dressing table, highchair, other furniture or carpentry project. Typically, machine screws are used in combination with inserts & bushings to attach large metal hardware items such as foot release bars, crib rods and mattress spring frames. Machine screws are also commonly used to attach a non-moving (stationary) side rail of a crib to the headboard and footboard. METRIC SCREWS ARE HERE!! CALL US!