The Hillman Group 829754 10 by 32-Inch Stainless Steel Nylon Insert Locknut, 100-Pack Product Description Nylon Insert Lock Nuts are also known as stop nuts. Lock nuts are used for fastening to a bolt when mechanically joining materials together. The bolt threads into the nylon material are located at the top of the nut. The purpose of the nylon insert is to prevent backing off or loosening from vibration. From the Manufacturer Nylon Insert Lock Nuts are also known as stop nuts. Lock nuts are used for fastening to a bolt when mechanically joining materials together. The bolt threads into the nylon material are located at the top of the nut. The purpose of the nylon insert is to prevent backing off or loosening from vibration. Features Nylon Insert Lock Nuts Have A Captive Undersized Nylon Washer That Creates Friction With The Mating Threads To Prevent Loosening Helps Resist The Effects Of Vibration And Other Forces Stainless Steel From The Brand Name: Hillman USA SHIPPING estimates delivery times and we work to get your item to you as quickly as possible and within those times, but please know it may take slightly longer than the estimate.