Spectrex - Precision Pocket Bubble Flow Meters for Air Sampling – Brochure
These unique units are: Portable (Weights: 1.5 oz; 2 oz; 8 oz.), Self-contained, Leakproof, All plastic, Provide instant soap bubble movement by depressing central cylinder 1/4`. Flow is established by timing bubble and reading off flow from a special `time` chart attached to the flow meter barrel.