The box chain - four flat sides forming a continuous square-section chain - has a geometric precision that the round cable chain does not provide. At 0.9mm in rhodium over sterling silver, it is the most delicate piece in the chain range: nearly invisible on the skin as a solo piece, but present enough to layer as the finest element in a necklace stack. Box chains photograph as clean and precise lines against the chest, making them a particularly strong choice for customers who document their jewelry looks. Spring ring closure. At 18 inches with an 18-inch length and this construction quality, this is the fine-jewelry-accessible daily chain at its most refined.