[Nonfractal]

The dark red endbell shows this to be an Si-MX16 23krpm motor.
However, you cannot ID a motor 100% from the endbell colour.
Managing the qualiity of the colour of the endbell seems to have been a problem for slot.it, so much of a problem that they have abandoned this method of identification. 
All new slot.it  S-Can motors are white endbell and the motor ID is printed/etched onto the can. 

MX16 "notorious" ???
Notorious for not being close to specification. These motors can run under 18k or over 25k. 
Whether you get a good one or a bad one is sheer dumb luck. 

The mx16 is my least favourite motor. I only use them when the ruleset for an event mandates this motor. 

AlanW