There are 2 Outside Air Temp Probes supplied by MGL Avionics. Only these Ambient Temp Probes (LM335) can be used with MGL Avionics systems.

Standard OAT Probe

The standard OAT probe has a red and a green wire. It is often supplied with a black sheath over most of the length.

Red is Signal
Green is Ground

(Some instruments have a dedicated Ground connection for the OAT probe - normally in the Main Power Connector)

Aluminum OAT Probe

The aluminum OAT probe has a threaded body and a nylon nut.

White is Signal
Blue is Ground

Or, in some cases:

Red is Signal
Green is Ground