There is a Side Imaging trolling motor puck---XTM 9 SI 180 T
The standard transducer for that unit is the transom Compact SI---XNT 9 SI 180 T.
To get the best performance from that unit, the HDSI transducer is the best since it is longer, has longer SI crystals that produce a thinner SI pulse and sharper images. XHS 9 HDSI 180 T
The transducer model you have is stated on a label about 12" from the plug.
Humminbird Helix 12 SI, 1198c SI, 1198c SI, ONIX 10 SI NT, 360, RC-1