A carrier puck comprising a body having an interior chamber, into which a receptacle to be held by the carrier puck can be inserted, the carrier puck comprising a deformable element, disposed at least in part within the interior chamber; and the carrier puck comprising a pressurizing mechanism configured and arranged to facilitate fluid-filling and/or pressurization of a region within the interior chamber, and in dependence upon said pressurization, the deformable element is forced to move inwardly of the interior chamber and into contact with a receptacle for securing the receptacle within the interior chamber of the carrier puck. In this way the available space within the interior chamber for accommodating a receptacle can be reduced about the receptacle, thus securing the receptacle, accurately and quickly in its location within the carrier puck.