Easy to use, on the beach or 250 feet underwater. 8 inch Spider The Impulse offers black-sand and salt-water operation and has a high sensitivity to silver and gold. It also detects all metals, and is built to take a beating. It is easy to use and provides over 100 hours of battery life. The Impulse includes a waterproof headset, and the control box easily converts to a belt mount unit. Backed by Fisher's Lifetime Warranty*.