The ornamental design for a mattress, as shown and described.
1. Mattress
1.1 : TOP PERSPECTIVE VIEW
1.2 : BOTTOM PERSPECTIVE VIEW
1.3 : Front
1.4 : Back
1.5 : Top
1.6 : Bottom
1.7 : Left
1.8 : Right
1.9 : PARTIAL ENLARGED TOP VIEW
1.10 : PARTIAL ENLARGED BOTTOM VIEW
1.11 : PARTIAL ENLARGED TOP PERSPECTIVE VIEW
1.12 : SECTIONAL VIEW
1.13 : SECTIONAL VIEW
The even dash broken lines show portions of the mattress that form no part of the claimed design. The long-dash, short-dash broken lines represent the boundaries of the claim and form no part thereof.
Reproduction 1.12 is an enlarged cross-sectional view taken alarm the center of reproduction 1.9. Reproduction 1.13 is an enlarged cross-sectional view a little bit above the center of reproduction 1.9 at the claimed four circular holes.