The Legge 3708 & 3709 differ in that the 3709 comes with a locking function when used with an existing "LEGGE 14" thumbturn. The 3709 also has a larger case size than the 3708. The sizes differ between the two & are shown in the specifications tab. They are steel case zinc coated. Sprung lever furniture with an 8mm spindle should be specifi..