TEMPUR® mattress holder set Mattress holder sets are recommended for free-standing use of the system frames to prevent the mattress from slipping. The appropriate holder set is specified directly with the respective model. The look varies depending on the frame product line. Which mattress holder set is suitable for which frame? TEMPUR® Premium Flex 500For single beds in sizes 80x200, 90x200 and 100x200, you need mattress holder set A. For double beds (and size 140x200) you need mattress holder set B. TEMPUR® Premium Flex 2000For single beds in the sizes 80x200, 90x200 and 100x200 you need the mattress holder set C. For double beds (and the size 140x200) you need the mattress holder set D. TEMPUR® Premium Flex 3000For single beds in the sizes 80x200, 90x200 and 100x200 you need the mattress holder set C3000. For double beds (and the 140x200 size) you need the D3000 mattress holder set. TEMPUR® Premium Flex 4000 For single beds in the sizes 80x200, 90x200 and 100x200 you n