pay attention : there is also the 4000 prototype , that is compared to the standard ball :
1) much softer ; the colour is RAL 7016 ( anthracite-grey )
2) the original finish was KXX ( extrem-rauh )
39 weight : 80 gr ; S= 40 ( at 20 ° ... at 30 ° around 55 ) , H= 26 ( !! ) circa
2) smaller ( 38 mm. ) and more " temperaturenfindllich " than the standard 4000.
3) without any "stempel" ( no numbers or other markings made by MR ).
in any case an extrem "banden" ball .. not easy to play but able to move away at bahn 5 ( abt 1) even under heavy rain.
I will later put some pictures with a comparison.