; Mercedes Sprinter (W906) NCV3 Original radio options - InCarTec

There are multiple original radio options in the Mercedes Sprinter (W906) NCV3, which option is the original fitted system?

MER-SPR1 - Audio 5/ Sound 5 MER-SPR1 - Audio 5/ Sound 5
MER-SPR2 - Audio 20 MER-SPR2 - Audio 20
MER-SPR3 - Audio 10 MER-SPR3 - Audio 10
MER-SPR4 - Audio 15 MER-SPR4 - Audio 15