How do I do sizes for gloves? Any ideas or guidelines?

Tech Specs:

Material:

DryRide Ultrashell (2-layer), DWR coating; [palm] Toughgrip; [lining] brushed microfiber 

Insulation:

Thermacore 

Removable Liner:

no 

Waterproofing:

DryRide Insane Membrane 

Closure:

drawcord 

Gauntlet:

yes 

Goggle Wipe:

yes 

Nose Wipe:

yes 

Hand-warmer Pocket:

no 

Recommended Use:

snowboarding 

Manufacturer Warranty:

1 year