The Volvo s60R/v70R front calipers are great upgrades for many vehicles. One draw back in many cases rotor width availability. 
  In the case of Volvo R calipers with Alfa Romeo rotors is that the rotors are a few millimeters narrower than the calipers max width capacity. 
  Additionally, shims can help correct ‘pad knock back.’ Shims can also help to slow and/or greatly reduce heat transfer from rotor/pad into the calipers and then brake fluid. 

  Two variations are available. 

  One version is a “wrap around” style like the much thinner OE shims. These come flat packed and will require fitting to your pads. The tads can easily be marked and the bent with an adjustable wrench. 
  The second version is a “drop-in” style which quite simply is fitted like the pads. These feature a tad that can be held during installation or aid in removal. This is especially helpful in track use when brakes may already be heat soaked. 

  These sold as a full set of four shims. Each individual shim measures 1.5mm (.060”) in thickness. Custom thickness can be added at request with no addition cost.