Adaptor to use a a Postmount brake in combination with a IS2000 Mount. The included wire is used to fix the screw. The adapter can be used as follows: 

fork with 160 mm mount:
SM-MA-F160P/S2 for the use of a 160 mm brake disc 

frame with 140 mm mount:
SM-MA90-R160P/S for the use of a 160 mm brake disc
SM-MA90-R180P/S for the use of a 180 mm brake disc
SM-MA90-R203P/S for the use of a 203 mm brake disc 

Designed for BR-M985 and BR-M988, but can be used on all Shimano 74mm-caliper brakes.

Features

• SM-MA90 series brackets are specifically designed for the new generation XTR-M985/988 disc brakes but can be used on all Shimano 74mm-caliper brakes
• These new adaptors are lighter, optimally machined, and even have areas drilled out to save weight
• Shimano Adapters are listed by: Rotor Size / Caliper Mount / Front or Rear / Bike Mount Tab / Mfg Part Number 
  
  

Specifications

• For instance a 160mm / 74mm / Front / 51mm IS / SM-MA-F160P/S
• Rotor Size = 160mm
• Caliper mount drill = 74mm
• Bike location = Front
• Mount on bike or fork = 51mm IS
• Shimano's part number = SM-MA-F160P/S