Corrosion resistant brass plated steel shackle. Windows make viewing combination quick and accurate. Black zinc alloy body. Combination can be easily changed. For luggage, briefcases, sports bags, backpacks, tool boxes, and cabinets. 646 has 13/16 in wide case, 1/8 in diameter shackle, and 3/8 in horizontal shackle clearance. 647 has 1-3/16 in wide case, 3/16 in diameter shackle, and 9/16 in horizontal shackle clearance.