Potter-Elvehjem PTFE pestle and glass tube 

All glass construction but with a PTFE pestle and an unground tube. Rounded shape on the lower portion of the pestle. Sample is progressively ground smaller in the rounded section. Homogenate is produced as the sample is forced through the cylindrical section. Recommend for use with softer tissues. Clearance between pestles and tubes is 0.004 in. to 0.006 in.