The IM-539 instruments have been designed especially to measure the Cylinder Heat Temperature (CHT) in Rotax® engines 912ULS/914.
 

The IM-539 is available in 57 mm diameter.
 

The instruments use a pointer thats turns 240º, witch gives them great resolution.
 

Their display areas are divided  into red, green and yellow zones in line with the ROTAX limits.
 

 This instrument Work with the VDO sender that is build in the ROTAX 912./914