This is the Snake Eyes v1 systems. This includes the interface unit, the DiamondBack Bullet Orientation Sensor (DBOS) and the Spitting Cobra Case Discriminator (SCCD).
This is for customers that do not currently have either system. If you have a DBOS or SCCD, then you only need the sensor head for the other system.
The mount choice is for the DBOS side of the system. The metal mount allows use of the DBOS in your choice of three stations (6,7 and 8). The plastic mount only allows use in one station (must select 7 or 8).