Garrett GTI 2500 Pro Metal Gold Detector LCD Backlight: to illuminate LCD screen for improved visibility. External Speaker and Headphone Jack: quarter-inch (14) size. Coin Alert Belltone Audio:Garrett sound for high conductivity targets. Last Mode Switching: switch from All-Metal into last-used discrim mode. Search Modes: All Metal, Zero, Jewelry, Custom, Relics, Coins, Pinpoint.