Aluminum Hand Twist Level Nut-Made by high quality aluminum,last much longer than plastic nuts.The torque of these nuts is large, making it easier to fine tune the hot bed.Metal nut is more powerful and will twist more tightly than plastic nuts. Silicone Solid Bed Mounts made from premium silicone, it is stable, durable and heat-resistant.Can help cutting back vibrations.These silicone buffers serve to replace on your heating bed original springs and it is no longer possible movement, your set levels remain.