A polo neck (US turtleneck) is the top part of some garments, such as leotards and catsuits, consisting of a high collar that comes up onto the neck and fits tightly round the throat. Sometimes the collar is designed to turn over.
People with latex fetish and spandex fetish often prefer garments with polo necks because they are more enclosive than garments with wide openings at the top.
If the garment opens at the crotch, it may be possible to pull the garment over the head. Otherwise, it is necessary to step into the garment from the top; to make this possible, there must be a zip (at front or rear) or a keyhole opening, usually at the rear.