The Southdown is a medium to small sized breed with a gray to mouse-brown face and lower legs and is polled (hornless).  Southdown are an early maturing breed with good lambing ability and average milk production. 

Mature weights for rams range from 190 to 230 pounds, ewes are slightly smaller and weigh from 130 to 180 pounds.  Fleece weights from mature ewe are between five and eight pounds.  The fleeces are considered medium wool type with a fiber diameter of 23.5 to 29.0 microns and a numerical count of 54 to 60.  The staple length of Southdown fleece ranges from 1.5 to 2.5 inches.