I managed to squeeze a single 3mm s,steel flapton in. But that highlighted a fault in the deck is completely dissected in two. So running a single coil is a pain as the second well fills up. I removed the clamp and.dremmeled a thin channel between decks. The 22mm clone version has a small gap between the decks which enables single coil builds. The flapton was great but got very hot. So I tend to stick to 2.5/3mm 26awg nichrome or kanthal coils. Plenty of flavour/vapour and less chance of a short. Plus it leaves a little more wiggle room to move the coils up or down to get the best position.