Index lengths in the AVITI OS Software version 2.5.0 or greater are not restricted with the exception of Elevate Index 1, which must have at least 4-cycles. Index lengths up to 55bp have been tested successfully, but not fully validated. We have not tested lengths greater than 55bp. Please note that Bases2Fastq can demultiplex a maximum index lenght of 16-cycles. Index FASTQ files >16-cycles can be generated.