Powers Fastening Innovations 03759 Spike Anchor - 1/4-Inch by 1-3/4-Inch Tie Wire Grade 8.2 Carbon Steel Pre-Expanded Anchor, 100 Per Box One Piece, tamper-proof anchor for use in concrete, block, brick or stone Formed with an "s" shaped configuration at the working end of the anchor to create an expansion mechanism 100 per box