99-18 YAMAHA YZF-R6: Yoshimura Oil Filler Plug (Works Edition) These engine plugs are actually stronger, lighter, and less prone to stripping than the stock units. But, most importantly, they make it obvious how serious you are about racing. Safety wire holes are machined during the CNC process; providing a clean look and easing installation for race sanctioning bodies...or more safety on the road.6061-T6 aluminum CNC-machined billet construction.Pre-drilled for safety wire.Anodized for lasti