Slider for pella casement windows

Thanks for reaching out to us. There are good odds that we can't provide this shoe by itself, but it would depend on a few factors. Before I recommend anything, can you show me a picture of the full operator in one shot? 

Can you also verify the brand of the window? Looking at what you have here, this looks like it could be Andersen, not Pella. I've never seen a Pella operator designed this way but it's also possible you just have something I've never seen before.