The Bluetooth device in the DL-V3 is a Class II bluetooth device. The BLuetooth Classes are desinated according to their range.
Class I -- 100m -- 330' -- within offices or between homes.
Class II -- 10m -- 33' -- several rooms.
Class III -- 1m -- 3' -- personal space or within an office cubicle.
Both paired Bluetooth devices have to be of the same class to communicate at the maximum distance otherwise the maximum range will be the range of the Bluetooth device with a lower classed range between the paired Bluetooth devices. Range may be lower with obstructions and other environmental conditions. Example A Class I Bluetooth Adapter communicating with a Class III Bluetooth GPS receiver will communicate at a maximum range of 1m.