Solid aluminum body. Three-dial resettable combination. Bronze plated steel shackle. 1,000 possible combinations. 620 has 13/16" wide case, 1/8" diameter shackle, and 3/8" horizontal shackle clearance. 630 has 1-3/16" wide case, 3/16" diameter shackle, and 9/16" horizontal shackle clearance.