The DuoPack is now in stock at Lectro.
Accepts SR/SR5P Series slot receivers
Dual 3.7V Li-Poly 3000mAh batteries
Up to 17 hours operating time per charge
Built-in recharging circuitry
Dual, balanced audio outputs
The DUOPACK adds a rechargeable battery pack to an SR Series receiver, allowing it to operate as a stand-alone device, further expanding the versatility of this product family.
Two lithium-polymer flat battery packs, one on each side of the assembly, provide enough capacity to operate the receiver for up to 17 hours per charge.
The control and connector panel includes audio and power connectors, an operating mode switch and battery charging circuitry. The unit can be operated from the internal batteries with an external power supply connected, or from external DC only.
http://www.lectrosonics.com/US/Wireless-IFB/product/482-duopack.html
Best Regards,
Larry Fisher
Lectrosonics