VV300b tube specs

I own a pair of tubes that are labelled VV300b, and came in a box labelled KR Audio VV300b. Neither the glass nor the base have any branding. The internal structure is identical to another pair of KR 300b tubes I have (WE clone type w full KR labeling on bottle) but the glass bottles are slightly different. Both are shoulder-types but one set has a higher "crown". In other words, the height of the bottle is higher from the shoulder to the top. As I said, even w a careful look, the internal metal structure is identical, the bases appear to be identical, even the apparent weight/transparency of the bottle. I've sent an email to KR's U.S. distributor but thought someone here might be able to shed some light on the provenance of these tubes and most importantly, what their specs are. I own a VAC 30/30 MKIII which requires that the 300bs meet WE specs and I would like to try them if possible.