In 1980, Philips introduced its model SL*18, which was a screw-in or bayonet mount lamp with integral magnetic ballast. The lamp used a folded T4 tube, stable tri-color phosphors, and a mercury amalgam. This was the first successful screw-in replacement for an incandescent lamp, using new rare earth aluminum lattice phosphors to solve the problem of lumen depreciation that would normally occur quickly in such a thin tube; however, it wasn't widely adopted, because of its large size, weight (over half a kilogram), pronounced 50 Hz flicker and 3-minute warm up time. It was based on the SL1000 prototype from 1976. In 1985, Osram started selling its model EL lamp, which was the first CFL to include an electronic ballast.