An over-frock coat is an overcoat designed to be worn over a frock coat as an overcoat in cold weather. A top-frock coat is also worn over a frock coat in milder weather. Shaped like the body coats popular in the late Victorian and Edwardian periods, the over-frock coat was cut in essentially the same way as the frock coat that was worn under it, although it would be larger overall to accommodate the frock-coat worn underneath. Like the frock coat, the over-frock would be single-breasted, with step lapels for informal occasions, like business, and double-breasted, with pointed lapels for formal occasions - weddings, funerals, balls, &c. The formal variety was known as a 'Prince Albert' overcoat. A frock-overcoat, like a frock coat, almost never has pockets.
Both the top-frock and over-frock coats were woollen, like most male garments of the time, and were made in varying weights, ranging from just 14oz for mild-weather topcoats, to 20 or 30oz for really cold weather. Wool was not a prerequisite, but was the most common material, and came in a range of qualities, the finest being that of a Merino sheep. Any material might be used, at a greater cost, including cashmere (from the Kashmir goat), angora (from the Angora rabbit), alpaca, or huarizo (from a hybrid of alpaca and llama). Evening over-frock coats, worn over Evening dress could be made from Mohair (from the Angora goat), which produced an additional sheen. Evening over-frocks often have silk revers, like the dress coat worn underneath. Both could be lined on the inside with fur of animals ranging from nutria or rabbit to silver fox or Imperial sable, depending on the owner's means. To order coat lined in sable, beaver, seal, or mink from one's tailor would be prohibitively expensive for most, and to own one would mark one as a person of immense wealth and status. The collars were very often velvet for warmth. Silk velvet was most expensive, while velvets made from cotton or other materials were more affordable.