Mechanical Bladder Pump users: an improved Barb ( 21573 ) is now available for use with a new, more rigid Polypropylene (PP) Tubing. The Barb makes installing the PP tubing easier, and the new tubing provides for better pump performance when sampling at greater depths (over 50 feet). The new PP tubing allows for higher sample integrity and quality for some analytes than Polyethylene Tubing (PE). PP tubing has similar inertness properties for VOCs as the more expensive FEP Teflon® tubing providing sample quality comparable to that of FEP at less cost. 0.25 in. OD x 0.17 in. ID available in 100 ft. and 500 ft. rolls. HDPE/Polypropylene Concentric Tubing available in 50 ft. and 100 ft. rolls.