... valve, durable and easy use.- Popular model among Senco rotary evaporators. Standard ModelR502DR503DParameters1Evaporating Flask (L)5L / F505L / ... , Bottom Discharge3L/S35, Bottom Discharge3Condensing Surface (m2)Vertical 0.29Vertical 0.294Rotation Speed (rpm)2-902- ... . A different experience-- Simple & RelexedSENCO, China made, Rotary Evaporator, Experiemental, Lab scale, Pilot Production, Water Bath, ...