Products Search by Part Number Products>Actuators>Linear Actuators>Interchange Type>C85>Knuckle Joints C85, Accessory, Knuckle Joints The C85 series add on piston rod knuckle joints. Accessory: knuckle joints Single and double types 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 -- KJ (Single Knuckle Joint) GKM (Double Knuckle Joint) Applicable Bore -- Pick an Option -- 4D (8, 10mm Bore) 6D (12, 16mm Bore) 8D (20mm Bore) 10D (25mm Bore) 4-8 (8, 10mm Bore) 6-12 (12, 16mm Bore) 8-16 (20mm Bore) 10-20 (25mm Bore) Options in: Gray are not compatible with other selected option value. Red conflict with another selected option value. Amber are not recommended.