SmartLock® closures to indicate secure lock. These containers work great for display, delivery, and takeout. They're sturdy, stackable, and help maintain food temperatures. Strong, rib-reinforced sides and back accommodate heavy items and provide enhanced crush resistance. Break-resistant hinge is flexible enough for easy closure and reliable enough for repeated openings and closings. SmartLock® system features a tight, audible click closure that helps ensure maximum food freshness.