Concealed Bolt Padlock 2-7/8" Master Lock®. ProSeries® keyed padlocks are designed for Commercial/Industrial applications. Lock body conceals shackle - defeats attempts to pry and cut. 2-7/8" (73mm) wide hardened solid steel body. 3/8" (9mm) diameter boron alloy shackle. Commonly used on vans, trailers, and vending machines. Use with Shielded Hasp #770.