Acoustically coupled Bell 103A-compatible 300 bit/s modems became common during the 1970s, with well-known models including the Novation CAT and the Anderson-Jacobson, the later spun off from an in-house project at Stanford Research Institute (now SRI International). An even lower-cost option was the Pennywhistle modem, designed to be built using parts found at electronics scrap and surplus stores.