The very rare fragmentation sleeve for the Eihandgranate was made of two halves that were exactly the same.
Both halves shown on my own set have factory markings " SCK " and a WaA-eagle stamped on the side.

Dimitar came up with an original document about the Splittermantel and the coiled frag sleeve for the stickgrenade.
First original document I've ever seen. It shows that already in September 1944 the egg frag shells were issued. Much earlier as I thought. Scroll down to see the scan.

First two photos © Rick Larson.

After WW2, the remains of the warproduction found its use in civilian products.
See what they did with the splittermantel : http://www.nachkriegszeit.de:80/hgrverwert.htm(german language)