It is a heavy duty, twin steel braided hose with a rubber covering. female thread of male thread. 8.7mm = 1/8" bsp = 9.3mm. 11.5mm = 1/4" bsp = 12.9mm. 15.2mm = 3/8" bsp = 16.2mm. 18.8mm = 1/2" bsp = 20.7mm.
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