This Joint screw M7 is suitable for Mutoh Viper 100 printers. This is the original Mutoh part (number DF-42127).
 
Printer compatibility
Mutoh Rockhopper 3 65
Mutoh Rockhopper 3 90
Mutoh Rockhopper 3 Extreme 65
Mutoh Rockhopper 3 Extreme 90
Mutoh Spitfire 65
Mutoh Spitfire 90
Mutoh Viper 100
Mutoh Viper 100 TX Extreme