The ornamental design for an adjustable cuff, as shown and described.
FIG. 1 is a rear view of the adjustable cuff accordance with the invention;
FIG. 2 is a top view of the adjustable cuff where the cuff is in a first secured position;
FIG. 3 is a top view of the adjustable cuff where the cuff is in a second secured position;
FIG. 4 is a top view of the adjustable cuff where the cuff is in a third secured position;
FIG. 5 is a side view of the adjustable cuff; and,
FIG. 6 is an enlarged view of the adjustable cuff shown in FIG. 1.
The broken line showing of the adjustable cuff is included for the purpose of illustrating portions of the article and forms no part of the claimed design.