Trident Tank Banger Underwater Signal Device-Black;

"Grip it", the best tank banger / noise maker available.
Slotted unbreakable oval ball provides easy grip, good looks and extra noise.
Who needs to spend a bunch of money on those high-end signal devices when you can simply attach this to your tank and gently pull on the plastic knob to make a nice 'clank' noise to get your dive partner's attention- Available in assorted colors.