A locking device is used for locking at least a piston associated with an operating element of a valve, a choke, a blowout preventer or some other unit used in the field of oilnatural gas drilling andor oilnatural gas production. The simulation system may be used for a laser rangefinder application and a laser designator application. Additionally, a method of choosing an annuloplasty device for implantation in a valve annulus is described. An upper pocket may be provided having a designation indicating that the upper pocket is to be used for storing medical supplies. It then transmits, to a payment gateway, a payment authorisation request, which comprises the payment details and a payment amount indicated by the retrieved quote.