Hydraulic hinges by Sun Design Plus come in sizes of 4 ½ by 3 inches and fit 8- to 12-millimeter glass. A paired set includes one spring hinge and one hydraulic hinge. The hydraulic hinge should be placed as the bottom hinge, with the adjustment screws facing up. The spring hinge needs to be placed in the top position. The hinges come in hold-open for high-traffic areas or non-hold-open options to help keep certain areas closed off for added privacy and security.