Ideal for vertical plankton tows when you need to sample a specific stratum in an integrated water column. After you’ve reached your desired depth and taken your sample, close the net by sending a messenger down the line, ensuring no further water gets through. Raise vertically at an even speed of 0.5 m/s. The truncated design improves filtration efficiency and consists of four parts: a tapered upper cylinder, the closing portion; a conical filtering net; an attached dolphin adapter; and a stainless steel Wisconsin dolphin bucket whose 10 oz. weight insures the net’s rapid descent. The closing portion consists of top nickel plated brass spring attached to a bridle, towing eye and release tab. A separate lowering and retrieval line is attached to the middle ring between the two cones.