100% graphite ferrule; upper temperature limit 450 deg.C. Soft; graphite is recommended for use with fused silica and glass. Reusable if not overtightened. One piece design requires no back ferrule. Packaged: 7-1/2 in. x 1-1/2 in. x 3/4 in. Plastic FID Case; Weight: 22.7 g.