A complete ZigBee set is sold. This set includes:
CC Debugger SmartRF04EB ZigBee Programmer
Adapter cable.
CC2531 ZigBee USB Sick
USB cable.
With the programmer the CC2531 ZigBee USB sick can be flashed with an alternative firmware e.g. CC2531ZNP-Prod.hexvon Koenkk.
There is also the adapter cable, without this adapter cable it is not possible to connect the CC2531 ZigBee USB sick to the programmer.
Please note: In some other offers, the programmer is offered without the adapter cable and without the CC2531ZigBee USB stick.
Instructions for flashing can be found here
blog.schmidhuber.org/barebone-zigbee-stick-cc2530-cc2531-with-the-smartrf04eb-programming