Tecmark Air Button [Raised Cone 7 8"hs Brown] (PT1 3130 02) unitedspas The 25 square foot rating The 25 square foot rating and 1 1 2 inch slip connection give this filter practical value because correct sizing and connection fit matter in preserving the intended flow and installation relationship of the system and nuisance shutdowns that can occur when the replacement does not correspond to the original system requirements This raised cone brown button is used with air switch systems to send a pressure signal through air tubing rather than direct electrical contact at the button location Air buttons are commonly used for jets