I have read in many threads of players stringing hybrids with different gauge strings. How many of you are using an illegal racket setup. According to ITF rules governing rackets and subsequent case rulings: ’1985 - Wording of the Rule - 3 cases added Case 1. Can there be more than one set of strings on the hitting surface of a racket? Decision. No. The rule clearly mentions a pattern, and not patterns, of crossed strings. Case 2. Is the stringing pattern of a racket considered to be generally uniform and flat if the strings are of a different gauge? Decision. No. Case 3. Is the stringing pattern of a racket considered to be generally uniform and flat if the strings are on more than one plane? Decision. No. Justification for the amendment The Committee recommend these three Cases and Decisions which clarify principles incorporated in Rule 4.