Large size anodised black Aluminium sight glass for your aluminium header tanks and breather tank catch tank projects etc These sight glasses are chemical resistant and are suitable for oil, engine coolant, power steering fluid Sight glass thread is male 1.1/4-11 BSP Sight glass boss is female 1.1/4-11 BSP Complete with weld in aluminium boss with a machined shoulder Do not confuse these with the cheap generic oil sight glasses, Please see my other auction for a plain alloy version and for the smaller versions in both anodised black and plain alloy Any questions contact Kinzy Fabrications