Choosing between a head with a 2mm (SUPA2) or a 4mm (SUPA4) gap is mainly aesthetically driven (taking into consideration that in outdoor installations a wider joint between the tiles is not as evident as in indoor installations). The advantage of using a head with a 4mm gap is being able to do the final height adjustments using the SUPAK tool, even after the floor is installed, without having to remove any pieces. In addition, the 4mm head can also be used with installations containing aluminum joists.