Lowbrow Customs oil pressure gauges are high-quality, with brass internals and a stainless steel housing. 1-3/4" diameter. Precision made to ISO standards and individually tested, these glycerin filled gauges offer an accurate oil pressure reading on your Harley-Davidson or other motorcycle. They are 1/8 inch NPT thread, and can be used with a variety of oil pressure gauge adapters and fittings available in both chrome or brass. Check out the Oil Pressure Gauges and Mounts category for gauges and fittings to go along with this adapter.