Like your oil filter Mark, have not seen it before.
Educate me please.
That looks like a MAP Cycle oil filter kit. I have one on my T140 too; they take trident oil filters.
Right, MAP Cycle. The backing plate is not part of the kit. The kit comes with two "figure 8" clamps, with which you can clamp the filter to the frame. But I don't have side panels for this bike, or a tool carrier, so I wanted to fill that space and hide the ugly side of the rear fender. My homemade backing plate bolts to the two frame lugs for the tool carrier with L-brackets.