Combination padlock
Student's lock
With four wheels and one master key 
Can be opened by key or combination
Each lock with serial number
Same key to work for all locks
Spreadsheet with all serial numbers and lock serial numbers
Code: resettable 
Material:
Shackle: steel 
Cylinder, housing, code wheels, and escutcheon: brass
Finish:
Housing: varnished 
Code wheels: nickel coating
Shackle: chrome plating
Weight: 257g
Packing: double blister packaging, 12 pieces per box, 8 boxes per carton
Carton size: 40.5 x 31.0 x 15.5cm