FAQ: How many indices are available with NEBNext Multiplex Oligos for Illumina (Unique Dual Index UMI Adaptors DNA Sets1-4)? 

Each set comprises 96 unique i5 and 96 unique i7 indices, therefore, providing up to 96 unique dual indices. Each well of the adaptor plate contains a unique pair of one i5 index and one i7 index. Used together, Sets 1-4 provide 384 unique dual index primer pairs for multiplexing.