Under the scheme, the government sells apartment flats to eligible public housing tenants and to low-income residents at prices below the market level, with discounts usually between 30 and 40 percent. It restricts resale of the units in the second-hand market to other families who qualify or, on the open market, after payment of a premium equal to the updated value of the discount given on the original purchase. As an ancillary scheme, the Housing Authority also entered into arrangements with local private developers to provide property for sale under the Private Sector Participation Scheme (PSPS).