Businesses in the doors category supply, make, fit, repair or replace doors for homes and commercial premises. Products may include internal doors, front and back doors, patio and bi-fold doors, garage doors, entrance systems and doors for offices or other buildings. Common materials include timber, uPVC, aluminium, steel and composite constructions, with choices of size, finish, glazing, handles and other fittings. Services can include measuring openings, advising on suitable designs and materials, supplying made-to-measure products, removing old doors and installing new ones. Some businesses also adjust or repair sticking doors, replace locks, hinges, handles and panels, or service garage door mechanisms. For commercial properties, suppliers may provide fire-resisting, access-controlled or high-security doors, with specifications depending on the building and its intended use. Work may cover the door frame and threshold as well as the door itself.