The FastenMaster Collated Cortex hidden fastening system is the fastest easiest way to hide fastener heads when installing Trex decking. The Cortex hidden fastening system is the fastest easiest way to hide fasteners in composite capstock and PVC decking boards - now it s 50% faster. Cortex can hide screws on stairs perimeter boards and more. Features Cortex No. 10 x 2.5 in. Saddle Torx Ttap Button Head Hidden Deck Fastener Made with high quality material 224 PieceSpecifications Finish: Epoxy Coated Head Type: Button Length: 2-1/2 Material: Steel Self Drilling: No Self Tapping: Yes Thread Type: Coarse Callout Size: No. 10 Drive Style: Torx Ttap Driver Bit Included: No Color: Saddle Indoor or Outdoor: Outdoor Weight: 4.75 lbs - SKU: ACHR174348