A material handler for a high pressure autoclave includes a combination of a body and a dished in cross section material carrier relatively arranged in a telescoping manner. The material carrier can be withdrawn from the body to a carrying position or telescoped into the body to eliminate the volume of the carrier. The body and carrier move in a passage to alternately position the carrier at a material transfer opening or in the autoclave. The carrier is telescoped into the body after material is removed therefrom, and while still in the autoclave, to eliminate its volume and avoid transferring atmosphere from one position to the other. The body and carrier combination has a sealed engagement in the passage.