LD Systems BM1

PZM (pressure zone microphone) or Boundary Microphone (hence its name BM1).
Omnidirectional semi-hemispherical. Made in China by LD Systems.
Miking coherent avoiding occasions of direct sounds and reflections, generating comb filters.
Powered electret phantom power 48V, output and mini-XLR 6m cable (ultra thin) finished in XLR.
Crown PZM of the patent fell into the public domain and there are several brands of "Boundary Microphones" quality at affordable prices.

OVERALL OPINION

I bought a pair of Realistic PZM time when there were still Tandy stores in France ... Realistic and these little cheap to me often favor.
I took these LD System for smaller microphones (yes, a cajon was not always a vent big enough ...).
Sound recording of meetings, recovery of jazz drums (2 PZM, made very close to the direct sound), and the classic bass drum and cajon recovery.
I do not regret having invested the few dollars (the 1/4 the price of a beta91).
Only complaint, the cable supplied is 6 meters and it is fine as a hair. I agree that it's quieter in the middle of a meeting table, but this cable will not last long. I have a shortcut to 30aine centimeters, and I put a "real" XLR cable as a result.