The slope "sweep areas" control ambient moisture and releases it harmlessly away from door sill and frame.
M-D Building Products
M-D Building Products offers a wide selection of door sweeps, thresholds, doorjambs, door bottoms, and drip caps to weatherproof doors. In addition, they offer push and kick plates and screen door grills.
Pemko offers a wide selection of saddle thresholds, brush weather-stripping, ADA ramps, astragals, continuous geared hinges and door bottoms to meet virtually any commercial or residential application.