Rk flight cases made by using clock to secure your instrument.lets know about the clock on flight case :

built-in clock:
Small shell lock: the lock of up and under part are the same size, with 36 mm high, with this kind of lock, flight cases request  height > = 100 mm
Medium-sized shell lock: lock up part is smaller than under part , respectively for 40 mm and 70 mm, high filling medium shell lock,  flight cases request  height > = 110 mm
large shell lock: lock is smaller than under part, respectively for 67 mm and 110 mm high, high loading large shell lock,  flight cases request  height > = 177 mm


Small lock may used in small case and Aluminum cases ：