These are made from 316 stainless steel, so they're as good as it gets. 
They are also wider so fill the groove on the manifold rubber perfectly. 
This one fits the bigger carburettors - 32mm VHSA, 34mm VHSB, 35mm Mikuni Etc.......
The third picture shows a standard clip on the left, and the one for sale on the right, to show the difference in thicknesses. The forth picture shows two clips on a manifold rubber (not included)
Suitable for Lambrettas and Vespas that use a rubber inlet manifold of this size.
 This is for a pair
 
Price includes VAT @ 20%