Yamaha actually don't make ear muffs and want you to use this screw in flush fitting. Whilst you can probably use a normal Nylex Bunnings fitting, this genuine Yamaha fitting has an extended neck so you can screw it right in for a good seal and still be able to plug your hose fitting on. Make sure you don't start the motor when using this fitting as it's designed to just push water through the head via the pressure of the hose.