If it is against 8.4cm than it could be 0.4mm
About fifty (50) yards.
900
7.5 - 4.5 = 3.0 more 7.5 / 4.5 = 1.6667 = 66.67% greater (2/3 more)
Mega is the prefix for 106 1000000 Kilo is the prefix for 103 1000 So Mega anything is 103 or 1000 times larger than the kilo of that thing