Most secure anchors available for securing your safe to standard 4" thick concrete floors with these flush mount concrete floor anchors. Red Head brand flush mount 2 " deep anchors allow you to move your safe without having to cut, or drill out protruding floor anchors. Just remove bolt, and the flush mount anchors stay in place for safe replacement without having to drill additional holes in your concrete floor. Easy to install. Drill into concrete 2" deep using a 5/8" mason bit, vaccum out hole, drop in anchor and tap in until flush, use punch or similar tool to expand anchor. includes 4 heavy duty Red Head brand anchors and four 1" x 1/2" grade 8 bolts.