This stainless-steel, 3-bladed paddle is 2.5" (63.5 mm) in diameter and has a 5/16" (7.9 mm) diameter shaft. It is available in 3 sizes ranging from a length of 8.75" (222 mm) to 18" (457 mm), with maximum vessel size of 8" (203.2 mm) for all 3 available lengths. This is a high efficiency paddle for viscous liquids or semi-solids. It is compatible with all the stirrers and stir testers we carry, including the following series: GT31, GT24, HST10, ST20, HST20, and HST30. A PTFE version of the 8.75" paddle is available as item # 21046.