Dimensionally, these look more-or-less similar to the ones Hairball sells (out of stock at the moment), but I wonder whether anyone has an idea of how operationally similar they are (or are not).
One of the listings I found advertised specifications that I couldn't make any sense of:
Input: 1000uA±5%
Internal Resistance: 50Ω±10%
I'm not sure whether these specs are totally not germane, or whether I just don't know enough to interpret them.
Nowhere in the listings does it say they conform to ANSI standards for VU meters, which might be telling. Then again, the >2x more expensive ones sold by Hairball don't specifically claim that, either.