Mine is a Iota model ITS-50R and located under the cedar chest insert at the foot of the bed.
Replaced it last June due to the printed circuit board blowing a hole in it.
Here is link to see pictures of what what a 30 & 50 amp models look like if you have a Iota. Not sure what other makes look like, but I imagine they are similar.
http://www.solarseller.com/iota_auto...tm#its___50_r_
Ron