The ornamental design for a sleeve for a mechanicalpencil, as shown and described.
1. A sleeve for a mechanical pencil
1.1 : Perspective
1.2 : Front
1.3 : Top
1.4 : Left
1.5 : Right
1.6 : Perspective view of compressed state
1.7 : Front view of compressed state
1.1 is a perspective view of a sleeve for a mechanical pencil showing our new design; 1.2 is a front view thereof; 1.3 is a top view thereof; 1.4 is a left view thereof; 1.5 is a right view thereof; 1.6 is a perspective view thereof showing the cushion spring in a compressed state; and 1.7 is a front view thereof showing the cushion spring in a compressed state; the sleeve comprises the cushion spring, and is disposed between a pipe accommodating writing leads and an outer tube; when a writing pressure is applied to the writing lead, the cushion spring is compressed; broken lines show environmental features that form no part of the claimed design; the back view is a mirror image of the front view; the bottom view is identical to the top view.