Years ago, I picked up an EIV CD 155 with a weird, stylized S etched or sandblasted on to the skirt. I assumed it was a one-off, or an anomaly, and assumed it was probably one of those mysteries I'd never solve. Then at the Platte City show a week ago, Dan Wagner had an EIV CD 545 with an extremely similar marking, so of course it had to come home with me to join its twin.

The obvious answer is this is a reference to Sediver, the company behind the EIV insulators, but this S is obviously stylized and not in a way that looks like any Sediver trademark I've ever seen.

Dan was thinking he'd seen some reference of this mark and referencing some particular military application, but I've scoured the hobby books and magazines since I've returned and found absolutely nothing on it.

Anybody else have an idea? Anybody else have an EIV with the same marking?