I put clear lens on the rear of my K12S. That is not a big deal as others have done it as well. I thought I could simply buy the lenses and bulbs off a K12R and do a swap. BMW made that difficult. While the lens is a direct swap out the bulb is another matter. The bulbs and sockets are different. The stock K12S buld has the two tits on the base of the bulb 180 degrees from one another. The amber bulb from the K12R has them at about 150 degrees so the bulb won't go in the socket. I was able to file one tit off to get the bulb to fit and have working rear turn signals. I am going to order up the socket/reflector from the K12R and do the job right. Would love to know why the two different bulb/socket designs.