We have them on our 2005 Cayman, but just on the front slides. From what I can tell, depending on what slide mechanics the slide has and the size of the slide, it is needed to hold the top of the slide out from tipping out when you go over a driveway approach too fast. One time I forgot to put them in and went a bit too fast and in the corning of my eye, it looked like the top tipped out
I would highly recommend using them!
I'm not sure if you're a talking about the same locks we have, but I've attached pictures on one of ours.