These are the same carbide file guides that the tool comes with. Made with a hardened anodized finish to resist wear. Make sure to add a drop of oil to the carbide before using. Metal shaving inevitably work inside, but a little oil prevents galling or carbide sticking.
Most chains are manufactured with a 30˚ angle cutting edge. This is a universal angle that works well on a wide variety of trees. However, by altering this angle with the accessory guides, better chain performance may be achieved. For example, when cutting soft wood, a steeper angle of 35˚ will cut faster and more efficiently. When cutting hard wood, a flatter angle of 25˚will stay sharp longer.