Several years ago, when we were beginning to increase the use of Ashaway MonoGut ZX and ZX Pro, it was not unusual to get a call from a client saying, “my coach says I should not be using polyester!” We could not agree more, and you are not using polyester!

You are using PEEK polymer! This string material was, and still is, referred to as Zyex with polymer production capabilities of Victrex in England.

Given the appearance of MonoGut ZX, Babolat Origin, and a few other non-polyester monofilament strings, it is not easy to distinguish these from stiffer polyester material strings. So know your string!

Single strand (monofilament) strings will have a gleaming surface unless they have been through a “roughing” process. So will monofilament strings of different materials. It is hard to tell just by looking, and that is what can create some confusion on behalf of the coach and subsequently, the player. So know your string!

If your racquet technician does not put a label on the racquet that identifies the material (or string), then be sure to ask what material you are using. The material choices may be natural gut, Zyex (PEEK), Nylon, and Polyester. The string construction may be referred to as a monofilament, multi-filament, single wrap, etc. however, the material will probably be one of these four.

Know your string! If you are unsure, contact your racquet technician or “Ask John” on this site, and we will try to help.