Color Light Track Block / Yard Signal. Gauge: H0. This is a simple track block signal without a mast for use in switch yards and station areas. The signal aspects change from Sh0 (red/red) to Sh1 (yellow/yellow). Track current can be controlled by means of the 72751 control box. Maintenance-free LEDs. Height without base approximately 10 mm / 3/8". A suitable control box is 72751. The 74371 signal cannot be operated with other controllers! Can also be used with the m84 decoder (60841) in digital operation.