The E-MAX Link is an advanced Bluetooth communication device that enables communication between multiple users up to 12 miles (line of sight). The E-MAX Link pairs to your current hearing protection wirelessly via Bluetooth with compatible muffs or plugs or with a 3.5mm audio cord for non-Bluetooth hearing protection. Included is a rechargeable battery (optional 3xAA use), with a USB-C charging cord. In the field or on the range, communicating with others has never been easier! Use the Link with any Caldwell hearing protection, including E-MAX Comms, Power Cords, E-MAX PRO, E-MAX PRO BTs, E-MAX Shadows and E-MAX Shadows Pro. Features: CONNECTS VIA BLUETOOTH TO HEARING PROTECTION ALLOWS COMMUNICATION BETWEEN MULTIPLE USERS COMPATIBLE WITH SHADOWS, POWER CORDS, PRO BT AND OTHER BLUETOOTH HEARING PROTECTION