Sylvan Arms VSB100: This incredibly durable and chemical-resistant upper receiver vice block module allows you to hold your firearm securely for cleaning, assembly, and repair. This vice block module also fits tightly into its corresponding Sylvan Arms cleaning plate, thereby safeguarding your firearm against finish and structural damage that may be brought on by the application of vise pressure such as scratches, dents, twists, and other structural distortions. This product is also great for general gunsmithing or completing your new AR-15 upper receiver build.