Grid - This refers to the width/diameter of the interlocking ceiling grid system the tiles are positioned within. To measure,
locate the edge of the grid that will be visible whilst the ceiling is fully constructed, if the grid system is still in place, this
will be the only visible part and is usually white. The most common grid width is 24mm and suits square and tegular edge
tiles. The narrow 15mm grid is usually only associated with microlook ceiling tiles.