2/4/20: it's a new frame, designed by Alexandre Arvinte.
I'm experimenting with very low top plate. so i can use small motors with top-mount setups.
i believe with higher top plate, you would need bigger motors to deal with a heavy weight ( battery ) hanging higher up.
also the frame is designed for a very low frame weight and setups.

i put mounting tape underneath fc/esc board and hold it down with electrical tape.
i don't have any problem with it so far. it's experimental. that's how i keep top plate very low, 7mm standoffs.

41g with 65mm props and built-in receiver and 5a board or 10a board.
fpv: runcam nano 3 + tbs pro32 + mount = 2.5g
motors: hyperlite 1103 8000kv
2s 450mah
65mm props
betaflight 4.1.x default. not a great tune but good enough.

top plate: 1mm
2.5mm bottom plate,