Amazon.com: LEGO TECHNIC 100 pcs BLACK AXLE SIZE 4 STUDS STUD LENGTH Cross Rod Short Mindstorms robot motor part piece 3705 NXT ev3 robotics : Toys & Games
Amazon.co.jp: Lego Technic Parts, Shaft Length 5 (Shin Ashe, Light Bluish Gray), Set of 5 (32073) Comes with handy measuring sheet (A4 print). : Toys & Games
gears - What are the dimensions of a technic axle? - Bricks