The ornamental design for a frame for a dustmask, as shown and described.
1. Frame for a dust mask
1.1 : Perspective
1.2 : Front
1.3 : Back
1.4 : Left
1.5 : Right
1.6 : Top
1.7 : Bottom
1.8 : Perspective view with the frame for a dust mask shown in use
This design is for a frame for a dust mask which is installed inside of the mask; the upper branch of the claimed design is located at the nose of the user and the lower branch of the claimed design is located at the chin of the user; further, the main frame connecting the upper branch and lower branch makes the side shape and contour of the entire mask; in reproduction 1.8 the claimed design is shown in dashed lines and the environment where the claimed design is used is shown in solid lines. The solid lines in reproduction 1.8 form no part of the claim.