Neck size: 38-400 threaded. Patented one handed operation frees operator's hands. Precision machined valves for smooth consistent operation. Cam-lock hinge keeps lid open and closed, reduces odors. No silicone or latex - perfect for ultra clean environments. Perfect for cleaning with cotton balls, pads, and brushes. Fits all Standard Menda HDPE, glass, and steel bottles. Dispenses approximately 2cc of liquid with each pump. Made in America for superior quality