http://www.compasseco.com/shop/products.html?maingroup=Muzzle%20Breaks&secondgroup=RWS
has them for $16. The pic looks like the 16mm, but the page is a little weird.
The Diana PN (hand written) on mine was 230-2652
The printed label says,
Barrel Weight,,Stabilisator,, 16 mm
for mod. 34-45/350 Magnum
Art.-Nr. 30523900
