1 x servo speed reducer adjustor board motor hub expander to grade crossing gate

price for 1 servo speed controller board( fit and must be used with my Master Board only )use with my Master board so that one Master Board may support up to 4 servos.adjust the servo speed so that the crossing gate may up and down slowly.2 groups controller and each group can be in different speed.default on board speed adjustor, and optionally remote speed adjustor ( sell separately )Specifications:Brand: WeHonest Model.Size: Please check it from the above photo.Package included:1 x servo speed controller board1 x cable to the Master Board( no paper instruction will come and you must come back here to view the online instruction upon receive )...