Amati yes. Amati made a lot of stencils. Not sure about B&H, but they did buy a lot in, so could have been from Amati.
The Amati stencil list below....
J. Keilwerth Toneking
J. Keilwerth Student
J.R. La Fleur & Son Alliance
J.R. La Fleur & Son Powertone