I was climbing a route that was at the upper end of my climbing ability. I was up about 6m and had thankfully stitched the route with 5 pieces (foreshadowing). I was unsure how to continue so I asked my belayer to take and sat on my top piece (a nut). As soon as I sat down my top nut blew and I fell further. When I stopped I was about 2m off the ground. And after checking, I realised I was sitting on my second piece, also a nut. This meant that three pieces of gear had blown during the "fall". I was very surprised at this, as all three pieces, I thought, were bomber pieces and would have easily held a fall. The pieces that pulled out were a nut at the top, followed by two cams, a yellow and a small blue.

I repelled down afterwards to replace the gear and try figure out what happened. Me and my climbing groups conclusion, a long with a few other climbers there, was due to the popular slate route, the rock was extremely smooth, not allowing any friction between the protection and rock. This shouldn't be an issue with nuts. But the nut was, admittedly, probably one size too small for the crack. But the lack of friction most likely meant that the cams, rather than camming out, just slid straight out of the rock

Thankfully the 4th piece held and prevented me from taking a ground fall.