Brother VR / PR series movable knife / thread cutter kit. A replacement kit that goes under the needle plate  on the commercial embroidery machine models.

When fitting these new parts they will need conditioning / bedding in. The spacers are to be placed under the movable knife. This will adjust the gap between the movable knife and the fixed and therefore make the two work better together. You may need 1 or all 3. 

Compatible machine models

 VR, PR1x, PR600, PR620, PR650e, PR655, PR670e, PR680w, PR1000e, PR1050x, PR1055x, PR1060w

 Part No; XC5882051