Originally made by "Dowty Group", they are also known as Dowty seals or Dowty washers. 1/8" BSP (similar to dowty) 10 x 16.0 x 2.0mm. 1/4" BSP (similar to dowty) 14 x 21.0 x 2.0mm. 3/8" BSP (similar to dowty) 17 x 24.0 x 2.5mm.
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