The TCS AR-15 Bore Guide may be the single most important cleaning tool for preserving the long term accuracy of your firearm. This tool keeps the cleaning rod perfectly straight so that it can not make contact with the sides of your barrel. To use this tool, simply remove the upper of your AR-15 style rifle and then pull the charging handle back and remove the bolt carrier group. Insert the bore guide into the upper, where the bolt carrier group would normally go. Center a patch treated with TCS Bore Paste on the back of the bore guide. Using a TCS Bore Jag on a TCS Rod, press the patch through the bore guide and into the bore. Repeat with TCS Solvent. This Mfg: Tcs