There are many needles and each has both an outside and inside diameter Please see the link below for all this information.
6.3 centimeters equals 63 mm.
1000 mm equals one meter
1.5 cm equals 15 mm.
1 km equals 100,000 mm
15 mm
6,800 mm
63 mm
457.2 mm.
84 mm ;-)
It equals 35 mm.
About 66 mm (65.99).
800 mm