These freezer hats for holding specimens in high pressure freezing equipment are available in brass only. The planchette designs are illustrated. The depths of cavity are 0.1, 0.2 and 0.3mm. Using two planchettes, one on another, in various combinations, allows cavity thicknesses of 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6mm to be achieved.