Hood not staying open on its own? That means the gas struts that hold it open are worn out and need to be replaced. These gas struts (AKA "gas spring assemblies") are OEM units from our supplier in England.
These are sold as a pair. One order is needed per car.
These are OEM items from Aston Martin, part# 6G33-16C826-AB (V8 and V12 Vantage) and 4G43-16C826-AB (DB9 and DBS).