Kimble 28950 KIMAX Short Stem 58° Angle Addition Funnels are constructed with heavy uniform walls and molded rims and fire polished stems to give a long service life. Funnels have a high resistance to chemical attack and mechanical and thermal shock. The 58° funnel angle is a Kimble exclusive, formed to an exact angle for rapid filtration. A piece of filter paper, when folded to form the filtering cone, forms a precise 60° angle. If the funnel is also 60°, as are the vast majority, then the only effective filtering area is down near the tip.