I think they are the bees knees and AHH the freedom

of no cable is just soooo good.
BUT it chews up batteries and you need to always carry spares. The volume on the head phone is set at mid point so every time you switch them on you need to adjust.
Only one AAA battery in the transmitter, velcro'd to the handy and safe location of the underside of Explorer arm cuff and two AAA batteries for the headphone.
I use them on My Explorer 1 and 2(hopefully the EX,SE soon as well)Whites DFX, EF Deepstar.
Very clear and can be very loud.
No drift and not susceptible to too much interference. You really know when the batteries are running down because that's what it sounds like, an external source interference.
I've made an extra external battery pod for the transmitter part. This one has a cable that plugs into a simple off the shelf adapter that brings up the male 3mm stereo jack to 6.5mm(EX 2 and others)
I also purchased the Macally Bluewave Bluetooth 712080.
I prefer these as the are a better headphone(bigger muffs and easier to transport and store)for metal detecting.
Has two AAA batteries in the transmitter and two AAA in the head phone. Is more versatile in what it does and has. The transmitter needs an adapter with a cable if your not happy with where it sits that is directly into the headphone socket and sits protruding out and rigid. Could be easily broken in not some protected.
Both headset's receiver and transmitter, in the case of both these two models, work with each others.
Just do a google search for either or others. There are plenty of sites and newer products coming out.
Out like someone to bring out a suitable transceiver system for my koss ur30s or any other headphones corded headphones, but have not seen anything in bluetooth worth while yet.
Who knows maybe sooner or latter we will see something.
Hard Nose Dave