Montana X-Treme (MTX) 1-Piece Cleaning Rod 17 to 20 Caliber 30" Coated Spring Steel 5 x 40 Female Thread 17 to 20 Caliber - Purple - Rod Diameter: . 22 to 264 Caliber - Red - Rod Diameter: . 270 to 50 Caliber - Blue - Rod Diameter: . 338 to 50 Caliber - Gold - Rod Diameter: .