Sealey Motorcycle Swingarm Locknut 4-Pin 50mm. This 4-Tooth socket is specially designed to remove castellated locknuts found on motorcycle swingarms and is also suitable for some engine mounting nuts. Model No. SMC22. Weight: 0.2kg. Nett Weight: 0.190kg. External Diameter: 50mm. Internal Diameter: 40mm. Internal Socket Depth: 6mm. Number of Pins: 4. Pin Width: 4.5mm. Pin Depth: 5mm. Drive Type: 1/2" Sq Drive.