The model no. for ARMORTEC 800 OFFENSIVE is almost correctly used by BFers as AT800-OF (OF is taken from the first 2 letters of OFFENSIVE) though some use AT800 OF, AT800 OFF, etc. For model no. of ARMORTEC 800 DEFENSIVE it should be AT800-DE (DE is also taken from the first 2 letters of DEFENSIVE) but quite a no. of Bfers use AT800DF instead. It also listed so at Equipment Reviews:rackets at page 7 for Yonex http://www.badmintoncentral.com/reviews/showcat.php?cat=4&page=7&sort=7&perpage=10&stype=  I think the correct model no. for ARMORTEC 800 OFFENSIVE/DEFENSIVE should be based on http://www.yonex.co.jp/badminton/products/racket/at800.html