Closed or Open Muzzle? Well, we got tech and decided to include an interchangeable muzzle system that allows you to choose depending on taste or conditions. Most experienced spearos opt for an open muzzle, but in challenging and choppy conditions a closed muzzle can be a blessing. If you look at the muzzle close-up image (without the rubber engaged), you'll see a small silver dot – this is the fastening bar for the open muzzle. Simply push the bar through and switch muzzle! Single or double band configuration can be easily changed.