Hollow glass pestle allows addition of ice water for chilling samples during homogenization. All glass construction primarily for manual operation. Interior of the pestle is hollow allowing to reduce heat generated in the grinding process. It can be used with a laboratory stirrer at low speed if a rubber stopper is inserted in the top of the pestle. A short steel rod (sold separately) completes the connection to the Jacobs chuck. The clearance between pestles is .004-.006. Ground tube Tooled pestle for use with rubber stopper (not supplied) Capacity: 7ml Stopper size: #1 **all glass construction primarily for manual operation. Interior of pestle is Hollow allowing to reduce heat generated in the grinding process. It can be use With a laboratory stirrer at low speed if a rubber stopper is inserted In the top of the pestle. A short steel rod (not supplied) completes the Connection to the collect or Jacobs chuck.