The shape of the waistcoat was evolving in the late 1760's through the 1770's, from a thigh- length garment with a slight sweep back from the waist, to a shorter-skirted style with a correspondingly sharper angle to the sweep. Waistcoats were usually single breasted, but from the early 1760's through the mid 1770's, a double breasted style was popular for outdoor and undress wear with a frock coat. Functional pockets were located at waist level, covered by flaps, with or without buttons and buttonholes, whose front edges often paralleled the skirt edge. The waistcoat should fit closely to the body, and the waist line should come down low enough to cover the waistband of the breeches, and the sweep should cover the edges of the fall. Waistcoats were sometimes made of materials of a contrasting color and texture to the coat and breeches.