This is a 1990 technical information catalog from WISA for the 100 to 1000 series air pumps. WISA 300 air pumps were sold as an
![Wisa Model 300 Pump for use with ET 2, 2.5, or similar air bearing tonearms Photo #2033935 - Canuck Audio Mart Wisa Model 300 Pump for use with ET 2, 2.5, or similar air bearing tonearms Photo #2033935 - Canuck Audio Mart](https://img.canuckaudiomart.com/uploads/large/2033935-wisa-model-300-pump-for-use-with-et-2-25-or-similar-air-bearing-tonearms.jpg)
Wisa Model 300 Pump for use with ET 2, 2.5, or similar air bearing tonearms Photo #2033935 - Canuck Audio Mart
![Wisa Model 300 Pump for use with ET 2, 2.5, or similar air bearing tonearms For Sale - US Audio Mart Wisa Model 300 Pump for use with ET 2, 2.5, or similar air bearing tonearms For Sale - US Audio Mart](https://img.usaudiomart.com/uploads/large/713216-1156d5cf-wisa_model_300_pump_for_use_with_et_2_25_or_similar_air_bearing_tonearms.jpg)
Wisa Model 300 Pump for use with ET 2, 2.5, or similar air bearing tonearms For Sale - US Audio Mart
![Wisa Model 300 Pump for use with ET 2, 2.5, or similar air bearing tonearms Photo #713217 - US Audio Mart Wisa Model 300 Pump for use with ET 2, 2.5, or similar air bearing tonearms Photo #713217 - US Audio Mart](https://img.usaudiomart.com/uploads/large/713218-671be117-wisa_model_300_pump_for_use_with_et_2_25_or_similar_air_bearing_tonearms.jpg)