Upright soundpost. At the rear the reedplate is removed, so that can be looked into the channels (chambers). Each flat-lying board chamber is connected with an upright channel of the soundpost over a common tone hole and supplied with wind. This means that when a key is pressed, the reed in the soundpost and the reed in the flat chamber sounds simultaneously. The result is a 2-choir sound, like it is the rule with almost all sqeezeboxes.