> For the complete documentation index, see [llms.txt](https://knowledge.illumina.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://knowledge.illumina.com/instrumentation/nextseq-500-550/instrumentation-nextseq-500-550-faq-list/000002580.md).

# How many extra cycles are included in NextSeq 500/550 reagent cartridges?

There are extra cycles (17 or 18, depending of the kit) included in NextSeq 500/550 reagent kits that can be used for index reads or to extend insert read lengths.

* 75 cycle kits: 92 cycles total
* 150 cycle kits: 168 cycles total
* 300 cycle kits: 318 cycles total

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| *For any feedback or questions regarding this article (Illumina Knowledge Article #2580), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000002580%20-%20Instrumentation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |


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