FIG. 1 is a front perspective view of a frame for a respiratory mask according to our new ornamental design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a top view thereof;
FIG. 5 is a bottom view thereof;
FIG. 6 is a right side view thereof, with the left side view being a mirror image; and,
FIG. 7 is a rear perspective view thereof.
The dotted broken line showing is included for the purpose of defining the boundary of the claim and forms no part of the claimed design.
The dashed broken line showing of unclaimed portions of the article is included for the purpose of illustrating environment and forms no part of the claimed design.