Bell does not require any additional air source. The bell must be mounted on a vertical surface and plugged in to a 110v outlet. With the hose attached you just drive over the hose or jump on it and the pressure change in the hose triggers the bell. It will ring with a light puff of air.I also supply a plug for the other end of hose. When a car drives over an attached hose, the bell rings. The item "Driveway Service Gas Station Signal Bell with25' of Hose-NEW Warranty" is in sale since Friday, November 28, 2014. This item is in the category "Collectibles\Advertising\Gas & Oil\Merchandise & Memorabilia\Other Gas & Oil Memorabilia". The seller is "hermans-spares" and is located in Erie, Pennsylvania. This item can be shipped to United States, Canada, United Kingdom, China, Mexico, Germany, Japan, Brazil, France, Australia, Russian federation, Denmark, Romania, Slovakia, Bulgaria, Czech republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Greece, Portugal, Cyprus, Slovenia, Sweden, South Korea, Indonesia, Taiwan, South africa, Thailand, Belgium, Hong Kong, Ireland, Netherlands, Poland, Spain, Italy, Austria, Bahamas, Israel, New Zealand, Philippines, Singapore, Switzerland, Norway, Saudi arabia, Ukraine, United arab emirates, Qatar, Kuwait, Bahrain, Croatia, Malaysia, Chile, Colombia, Costa rica, Dominican republic, Panama, Trinidad and tobago, Guatemala, El salvador, Honduras, Jamaica, Ecuador, Luxembourg, Viet nam, Uruguay.