A dispenser for dispensing a fluid from a container T having an inlet for mounting to the container so as to receive therethrough the fluid, and an outlet which is adapted to open to release fluid therefrom when a predetermined pressure is applied to the fluid in the dispenser at the outlet, and to close to retain fluid in the dispenser at a pressure less than the predetermined pressure. The substrate holder has a base and a cover having an opening defined therein and positioned to place the substrate between the base and the cover. A Certificate authority distributes certificates and certification revocation lists to the devices via the access point. The invention also includes a method of forming an assembly containing MRAM devices.