Market Leader in Plunger & Cooler Manufacture. Hunprenco are the world’s leading manufacturer of Plungers and Coolers to the Glass Container Industry. The company was established in 1969 by Mr E Neesom, and now employs over 100 personnel that include highly skilled machinists and people with vast knowledge of production methods in glass container manufacture. In May 2009 it was accredited with ISO 9001 and later that year completed a major investment to maintain its status as the market leader.