Blue Thread Locker locks set screws, axle and drive nuts, engine mounting screws, or any screw that keeps your R/C airplane, helicopter, car, or boat from coming apart. But Z-42 Thread Locker isn't just for hobbies, use on autos, boats, snow mobiles, lawn equipment, tools, bicycles, and even toys. Anywhere fasteners are subjected to vibration that can cause them to loosen and fall out Z-42 Thread Locker helps to keep things together..