An extensional rheometer analyzes the thinning and breakup of a fluid filament, providing valuable information about a material's physical properties. The CaBER 1 from Thermo Material Characterization (Madison, WI; 608/327-6777) can function as either an analytical instrument or a quality control tool. Standard features include computer control, a Class 1 laser micrometer, a linear motor drive with variable speed, automatic repeated testing, and a closed temperature-controlled sample chamber. The rheometer is ideal for applications involving adhesives, industrial resins, surfactants, and associated polymers.