Clean the gas tube without disassembly. Insert the clear Guide Tube (included in the AR Cleaning Kit) over the end of the Gas Tube. Hold the end of the gas tube brush close to the bristles and slowly feed the brush through with short strokes until it reaches the end. Repeat this step if necessary. Please note: You need to have the clear guide tube in order to feed the brush down the gas tube properly. This is included in the AR Cleaning Kits. This kit serves as replacement brushes for the kit. Mfg: Iosso Products SPECS: Qty: 2. Overall Length: 21"