The ornamental design for a fastener, as shown and described.
1. Fastener
1.1 : Front
1.2 : Top
1.3 : Bottom
1.4 : Right
1.5 : Cross-sectional
1.6 : Perspective
1.7 : Perspective
1.8 : Front view of male part
1.9 : Top view of male part
1.10 : Bottom view of male part
1.11 : Right view of male part
1.12 : Cross-sectional view of male part
1.13 : Front view of female part
1.14 : top view of female part
1.15 : Bottom view of female part
1.16 : Right view of female part
1.17 : Cross-sectional view of female part
The left side view is the same as the right side view; the male and female parts are attached on separate tapes; the male part is slidable on the tape but the female part is fixed on the tape; when the male and female parts are engaged, the position of the male part is fixed.
The broken lines shown in the drawings illustrate portions of the fastener that form no part of the claimed design.