Are afraid of confusing too many keys? Does the locker key need to be marked? Do you till looking for number key tags?
That is right .
This one :
Number Key Chain, Dedoot Pack of 30 Key Number Tags Number Key Ring Stainless Steel ID Tags Numbers for Dormitory House Lockers Keys, 23mm Diameter
Just what you are finding and needing!

Material: stainless metal
Diameter size:
Number key chain: 23mm/0.9inch
Key ring: 20mm/0.79inch
Color: sliver

Be suitable for:
Home, hotel, restaurant, luggage office, locker key, food, plants, for coding identification. Help to organize your keys or other things quickly and well.

Package included:
30 x number key tags