The common turtleneck, also known as a roll-neck or polo neck, has existed since the 15th century but has only reached popularity in the early and mid-20th century. Most turtlenecks are made of sweater fabric, knitted, or crocheted fibers, and are often designed to warm the body. Just like crewneck sweaters, turtlenecks may have different gauges, meaning the fineness of the stitching. Fine gauges appear smoother and are often seen as more formal, able to fit under an oxford shirt or suit as an alternative to a necktie. Heavy gauges, like those seen under a fisherman’s overcoat, offer a great deal of insulation for the cold seas or winters. Medium gauges offer a nice middle ground and look great styled with a simple jacket.