Fortress Building Products Hulk 1.75-in Black Hidden Fastener 500-sq ft (125-Pack) in the Specialty Fasteners & Fastener Kits department at Lowes.com
Myard Universal Hidden Deck Fastener Clips for Grooved Edges of Composite Decking Boards to Joists, 1/4" Gap Spacing, with Square Driver Bit (500-Pack) - - Amazon.com