MF7 Primary Support Channel. MF7 Channel at 3.6m connects with MF5 Ceiling Furring Channel Section and MF6 (MF6A) Perimeter Channel by use of the MF9 Connecting Clip as a component of a Metal Framing suspended ceiling system that is ideal for commercial and domestic applications where ceiling height may be varied to suit requirements. Concealed grid suspended ceiling systems are suitable for most internal dry lining applications and are ideal where services need to be accommodated and when upgrading and protecting existing structures.