A keyboard key type developed by synthesizer manufacturers. Semi-weighted keyboards combine the spring-loaded mechanism of synth actions with the addition of light weights attached to each key, similar to those found in weighted action or hammer action keyboards. The result is a key that has light-to-moderate resistance when you press it, with a rebound to the “up” position that is a little slower than the springiness of a synth action. Semi-weighted actions appeal to players who don’t need or want the full resistance of a weighted action. Players accustomed to the feel of a Hammond organ also like semi-weighted actions, with one important exception: while the Hammond (and other electronic organs) uses a waterfall-style key that is slightly rounded at the top edge, almost all semi-weighted actions have a piano-style overhang, or lip, on top, making some organ techniques like smears and glissandos difficult and often painful.