I've had a Slider on my 3G for a year. Fit like a glove. I transferred the case to the new 3GS. The bottom piece doesn't sit flush to the rest of the case at the seam...you can see a bit of chrome through the gap. And the bottom piece nearly falls off if you look at it wrong. When it's in place, there's a slight rocking left and right. On the 3G the bottom was nice and tight. All in all, not a great fit. I feel like the 3GS might be .025mm smaller at the base curve. I have a new Slider on order. Maybe it will fit better.