The Efail Fach television relay station is sited on a hill west of the villages of Efail Fach, Cwm Pelenna and Tonmawr. It was originally built in the 1980s as a fill-in relay for UHF analogue colour television serving all of those settlements. It consists of a 15 m self-supporting lattice mast standing on a hill which is itself about 160 m above sea level. The transmissions are beamed to the east towards the Pelenna valley. The Efail Fach transmission station is owned and operated by Arqiva.
The "Transmission Gallery" site claims that the Efail Fach transmitter re-radiates the signal received off-air from Cilfrew television relay station near Neath, itself a repeater of Kilvey Hill at Swansea. However, Efail Fach used the same frequencies as Cilfrew in the analogue TV days, and shares two frequencies with Cilfrew in the digital TV era.
OFCOM claims that the site re-radiates Kilvey Hill directly. Efail Fach does indeed have a clear line-of-sight to Kilvey Hill (which is about 11.6 km away at a bearing of 259.5°).
When it came, the digital switchover process for Efail Fach duplicated the timing at the Kilvey Hill parent station, with the first stage taking place on Wednesday 12 August 2009 and the second stage was completed on Wednesday 9 September 2009, with the Kilvey Hill transmitter-group becoming the first in Wales to complete digital switchover. After the switchover process, analogue channels had ceased broadcasting permanently and the Freeview digital TV services were radiated at an ERP of 2 W each.