Sight glass with polycarbonate window and 3/4" aluminium thread. Its function is to measure the oil level contained in the compressor air pump. OTHER SIZES AVAILABLE: 1/2" BUSINESS HOURS Monday to Friday from 9:00 am to 6:00 pm. SHIPPING POLICIES If you purchase the product before 1:00 pm, it will be shipped the same day. Otherwise, the shipment will be made the next day (if it is possible). SPECIAL DESIGNS AND FABRICATIONS Ask our executives about special fabrications. We have a machining and micro-machining workshop to make custom parts. We work with stainless steel, brass, aluminum, Teflon, etc.