SOTAR used the Leafield C7 valves prior to the D7.
The boots on the C7 & D7 are not inner changeable meaning you must replace the entire valve.
The Leadfield C7 valves are made from ACETAL (POM) plastic providing high strength, chemical and ozone resistance.
The seal is designed so that it cleans the seal surface as it operates; this also reduces the risk of leakage due to dirt contamination.
When the cap is fitted the rugged retaining strap is hidden from view to prevent snagging on other equipment. Simple cap replacement - it does not require the valve to be removed.
SOTAR transitioned from C7 valves to D7 February 20, 2015. Please contact us directly should you have questions on what valve you have.