The top of the ACE family, the 400 has new Iron Audio feature, a powerful DD coil, a higher frequency, and volume control headphones. FeaturesDIGITAL TARGET ID - Numeric identification scale from 0 to 99. Identifies a target metal's conductivity.ELECTRONIC PINPOINTING - This non-motion All-Metal Mode function is used to precisely locate a detected target's position.IRON RESOLUTION - Increased resolution (more pixels) allows more precise control of how much iron discrimination to apply. Very useful in areas where desired treasure targets are being masked by iron trash.GRAPHIC TARGET ANALYZING - Simultaneously shows a treasure target's conductivity and the detector's discrimination pattern. Included:Garrett ClearSound Easy Stow Headphones with volume controlACE Environmental Cover-UpSearchcoil cover