Pneufit C composite fittings are ready to use offering fast assembly with no need for tools. Releaseable stainless steel grab ring to grip nylon or PU tube (85 or 95 durometer). Nickel plated brass components. Immediate quality sealing using silicon free U packing. Internal hexagon on straight adaptors allows assembly in confined spaces. Red release sleeve indicates metric tube size. Reusable 'O' ring seals on parallel threads. Mounting holes on all union fittings.Specifications:C00230406: Tube O/Dia 6mm - 4mm.C00230604: Tube O/Dia 4mm - 6mm.C00230608: Tube O/Dia 8mm - 6mm.C00230804: Tube O/Dia 4mm - 8mm.C00230806: Tube O/Dia 6mm - 8mm.C00231006: Tube O/Dia 6mm - 10mm.C00231008: Tube O/Dia 8mm - 10mm.