The YOYO Spacerbox includes 48 individual bearing spacers in 6 different sizes. This is beneficial as each wheel core will have slightly different tolerances. By using different measurement bearing spacers in each wheel (through trial and error or using the Rigour Spaceometer), you can dial your wheels perfectly. 

Includes
8 x 9.95mm
8 x 10.00mm
8 x 10.05mm
8 x 10.10mm
8 x 10.15mm
8 x 10.25mm