Hummingbird ff/gps

I just got my through hull transducer, it came with a large black puck, It appears to me this thing is not used on a T15. Is anyone using this thing?

Need more info, pics, or numbers.

Does it look like this?

Its just used as a spacer if needed I did not use it on mt T13. Don't forget to put a little GOOP on the threads when installing it will keep it in place.

Pat R

Does it look like this?

Yea that is it, I guess don't use the puck and goop the thread as the post above says, thanks for the info guys.

Mark