Products Search by Part Number Products>Actuators>Linear Actuators>Standard>CM2>Knuckle Joints CM2/CM2-Z Accessory, Knuckle Joints Series CM2-Z add on single and double piston rod knuckle joints. Single and double knuckle joints Available for all bore sizes Configuration Options Select Product Options Select values from the drop down lists or make appropriate selections to configure the part number. Type -- Pick an Option -- I (Single Knuckle Joint) Y (Double Knuckle Joint) Applicable Bore -- Pick an Option -- 020 (20mm) 032 (25mm, 32mm) 040 (40mm) Options in: Gray are not compatible with other selected option value. Red conflict with another selected option value. Amber are not recommended.