Montblanc Clamping Ring for -2 or -4 Series + MB31

This is the tiny, thin, silver colored ring on the connector, between the front section and the transparent ring that always gets lost during maintenance and repairs.  These clamping rings can be used on any -4 series or -2 Montblanc pens.  Newly manufactured, made of stainless steel. 

The -2 size fits a Montblanc pen with a two digit model number that ends in a 2, as well as the Montblanc 31.  So it is designed to fit Montblanc 2 series pens such as a Montblanc 22.
Dimensions for -2 series Montblanc pens:
Outer Diameter: 10.7 mm
Inner Diameter:  9.0 mm
Thickness: 0.38 mm

The -4 size fits a Montblanc pen with two digit model number that ends in a 4: so Montblanc pens 14, 24 and 34 Silver colored. 
Dimensions for -4 series Montblanc pens:
Outer Diameter: 11.36 mm
Inner Diameter: 9.60 mm
Thickness: 0.38 mm