This is a conductive material known as "Velostat" or "Linqstat", its suitable for wearable applications. The material is pressure-sensitive: squeezing it will reduce the resistance, so it's handy for making flexible sensors using the material. Its less expensive than off-the-shelf pressure or bend sensors. It comes with a 11"x11" (28cm x 28cm) 4mil (0.1mm) thick piece.
Check this out: Tutorial
Contents and Image taken from Adafruit