This is the picture of the boat wiper motor. it is 2 speed and as you can see, it has different holes you can select on the wiper crank arm and under the lock washer you will see a slotted mount for changing the ark of the wiper. The unit is about 1" longer than a dollar bill and 4 1/2" deep, not counting the post for mounting the wiper arm. The mechanism converts rotary motion to ark motion in very a small unit. A clever guy could just duplicate the mechanism, but like I said I bought this one for $5.00 at a garage sale. I haven't tried it yet but I'll be replacing my Blazer unit with this one.