It is a spike receptacle base of the diameter of 41mm of the Africa ebony used for oboe etc. Independent, it places under a speaker, amplifier, etc. combining PB-20, and carries out. When a metaled spike is received, in metal, resonance is suppressed and the sound which was clear and became tight by intrusion of a moderate spike is obtained. Although it is of the same type as PB-10, since size is large, the stability at the time of installation increases.

External form measure: the diameter 41 mm the height: 14 mm / depth of the form department: 3.5 mm
Material: the African ebony (specific gravity about 1.4)