They need a Danfoss RX1, RX2 or RX3 receiver to be paired with. There are 9 available initially but you can buy them individually or any quantity you need whilst they are still available.
DANFOSS RET-B RF WIRELESS BATTERY ELECTRONIC ROOM LCD ROOM THERMOSTAT 087N727000
Danfoss TPOne-RF+RX1S Wireless Programmable Thermostat With Receiver 087N7854
DANFOSS RET B - RF WIRELESS BATTERY ELECTRONIC ROOM THERMOSTAT LCD 087N727000
heatmiser UH8 RF Mini- The New RF Wireless Stat "Space Saver" Wiring Centre
Worcester Bosch Comfort+ 2 II RF Wireless Room Thermostat with RF Key Card
Myson Mprt RF Wireless Programmable Room Thermostat Radio frequency/wireless
