40 feet seems a bit too far for over-the-counter Bluetooth products. I run a Bluetooth mic on my amateur radio (ham) 2-way mobile radio and get 15-20 feet of range max.
Granted, the manufacturers of the mic are trying to get as much time using the mic before recharging and have kept the power consumption low (after all, normal use would only need 5-10 feet of range inside a vehicle. But I would check the specs of any Bluetooth product regarding range before buying it. I believe there are regulations regarding max output of Bluetooth devices also? 40 feet seems a bit much to expect. And since I haven’t researched the range of these devices I may be mistaken. Can anyone better advise on the range question? What are these devices advertising for max range?