Since I bought mine, Foof have changed the inner lining from a satin-type thing to a fleece-type thing (they probably describe it better than that). As a result they've been able to go for more 'generic' sizing because the fleece has depth that obviously compressses when you put the phone in the case. Am just speculating because I've not used an invisible shield, but would guess that a tiny bit of extra bulk wouldn't be a problem (they use the same case for both gen iphones, for example, and I think the old one is thicker than the new one).