The Advent 2-In-1 Gap Tape is a unique product for normal and internal measurements. It has a double sided, non reflective steel blade with metric and imperial graduations. Contained with an ergonomically designed ABS case with a moulded rubber grip for increased comfort. With normal measurements on the top of the blade, the reserve blade markings take into account the tape case dimensions, so when you measure internal spaces you simply butt the case up to the end and read the measurement.