Monitor tyre pressure at a glancefitted in secondspressure range 28 36 psisupplied as a pack of 4shortcode tabdescriptionget an instant visual update on your tyre pressure by replacing your valve caps with these aluminium all weather tyre pressure monitor caps fitted in seconds green yellow and red tells you safe caution or danger simply inflate the tyre to the required pressure then screw the monitor cap on tight and it will show green if the type pressure falls the cap will show ye