You get a bag of 20; this spike is about one inch in height and thin. Each spike comes with a screw for attachment.

Screwback Spike description
height: 1 inch (25 mm)
base: 5/16 inch (8 mm)
color: silver
base: steel
screw type: metric- 4/.7 coarse, 1/2" length
shape: round thin tree-like spike