These high grade Dubilier PIO capacitors are ex military, The PIO dielectric is sealed in to the aluminium case using a rubber O ring seal to prevent physical leakage.
These 0.1uF 500V devices are sized 55 x 10mm
As you can see from the following photos, these capacitors were packed in threes in a waxed paper bag which was then oversealed into HDPE packing. These devices have been tested for capacitance and show nominal capacitance, testing at working voltage using my Megger BM403/2 as you can see gives an infinite int. resistance showing exceptional grade capacitors. Sonically, these are lush and smooth sounding, a must for high voltage applications or indeed for low voltage applications wheer more headroom is required. You will not find better and these trounce the sonic performance of Jensens and beeswax moderns!