You are offering Anti-Biotin MicroBeads and Streptavidin MicroBeads. When should I choose which reagent? 

Anti-Biotin MicroBeads do not bind to free biotin that has been released from dead cells, but only to bound biotin, as is the case for biotinylated antibodies.

For this reason our general recommendation is to use Anti-Biotin MicroBeads for all biotinylated primary antibodies (i.e., when following an indirect isolation strategy), as they enable an efficient sorting of cells with strongly and weakly expressed antigens.

Note: Anti-Biotin MicroBeads only recognize biotin that has been coupled chemically and not enzymatically to the antibodies or ligands. If the biotin in your application has been enzymatically coupled, use the Streptavidin MicroBeads instead.