# Index selection and FAQ for Illumina DNA PCR Free

**Is Illumina DNA PCR-Free compatible with all Illumina indexes kits? Which indexes can be used with Illumina DNA PCR-Free kit?**

* Illumina DNA PCR free is compatible with the 10 bp IDT for Illumina - DNA/RNA UD Indexes (formerly, the IDT for Illumina Nextera DNA Unique Dual Indexes).

**Where are the sequences of adapters, sequencing primers, and indexes used in Illumina PCR-Free library prep?**

* All publicly available sequences can be found in the [Illumina Adapter Sequences](https://support.illumina.com/downloads/illumina-adapter-sequences-document-1000000002694.html) Document.
* Sequencing primer sequences are proprietary.

**How to choose index combinations for libraries if pooling a low number of libraries in a sequencing run?**\* See the IDT for Illumina-DNA/RNA UD Indexes section of the [Index Adapters Pooling Guide](https://support.illumina.com/downloads/index-adapters-pooling-guide-1000000041074.html) for guidance.

* See [Balancing sample coverage for whole-genome sequencing](https://www.illumina.com/content/dam/illumina/gcs/assembled-assets/marketing-literature/illumina-dna-prep-pcr-free-index-correction-tech-note-m-gl-00005/illumina-dna-pcr-free-index-correction-tech-note-m-gl-00005.pdf) technical note for approximate expected index representations.

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| *For any feedback or questions regarding this article (Illumina Knowledge Article #3471), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000003471%20-%20Library%20Preparation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |


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