Speedless motor speed controllers, 5 pieces for $ 40 - the price is quite attractive, ordered (especially as the new quadcopter builds began). I did not regret.
They came without identification marks and instructions. By sight all sorts of pentium-30A sold under the brands jDrones, HobbyWing, Mystery, etc.
This instruction came up for programming. dl.dropbox.com/u/1638929/other/esc/ESC_Manual.pdf
A bit of appearance:
and light erotica
The only negative is that they work only at a frequency of 8kHz, although it worked fine with the MultiWii project.
UPD: Regulated custom firmware - more info here, here and further right here in bourgeois