a. XX-170R - non proportional. works with 2 pin toys gearbox type of servo
b. XX-162R - proportional. works with standard 3 pin servo
c. XX-184 - new non-proportional receiver board
d. XX-318R - old D12 receiver board
e. XX-339R - new D12 receiver board
f. XX-363T - D12 Remote board
g. XX-412R - new proportional receiver for B & C series RTR. Release Year 2022.