Hole size is ~3.1mm for M3 Screw 

Color: White 

High Temperature plastic (200C, just one model is 270C - TO220 270C) 

Usage is to isolate electrically transistor or other components from the Screw mount 

Depend from the usage, you may need silicone sheet under the component 

It is 100% Electrical Insulator 

TO-220 150C Description: 

Hole size: 3mm for M3 Screw 

Diameter: 6mm 

Color: Beige 

Hight: 2.7mm 

TO-220 Description: 

Hole size: 3mm for M3 Screw 

Diameter: 6mm 

Color: White 

Hight: 2.7mm 

TO-220B Description: 

Hole size: 3.1mm for M3 Screw 

Color: White 

Height: 4.5mm 

TO-220D Description: 

Hole size: 3mm for M3 Screw 

Diameter: 6mm 

Color: White 

Hight: 5mm 

TO-3 Description: 

Hole size: 3mm for M3 Screw 

Diameter: 8mm 

Color: White 

Hight: 4.5mm