Product Class: Other

NEBNext® Ultra™ II End Repair/dA-Tailing Module

Product Introduction

This module is part of the Ultra II workflow, and is optimized for use with the NEBNext Ultra II Ligation Module (NEB #E7595), for Illumina®-compatible library construction. 

This module is also compatible with some Oxford Nanopore Technologies® workflows, including some involving COVID-19 research.

Kits that include reagents for every step in the Ultra II DNA library construction workflow are also available (NEBNext Ultra II DNA Library Prep Kit for Illumina (NEB #E7645) and NEBNext Ultra II DNA Library Prep with Sample Purification Beads (NEB #E7103).

Catalog # Size Concentration
E7546S 24.0 reactions
E7546L 96.0 reactions
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Product Information


The NEBNext Ultra II End Repair/dA-Tailing Module has been optimized to convert 500 pg-1 μg of fragmented DNA to repaired DNA having 5′ phosphorylated, 3′ dA-tailed ends. The module is optimized for use with the NEBNext Ultra II Ligation Module (NEB #E7595), and is part of the Ultra II DNA workflow which enables high yield preparation of high quality libraries from 500 pg to 1 µg of input DNA.

This module is compatible with Illumina workflows and with several Oxford Nanopore Technologies workflows.

For Illumina library construction, the NEBNext Ultra II End Repair/dA-Tailing Module is designed for use with the following:

• NEBNext Ultra II Ligation Module (NEB #E7595)
• NEBNext Ultra II Q5® Master Mix (NEB #M0544)
• NEBNext Oligos for Illumina (NEB #E7335, #E7500, #E7710, #E7730, #E6609, #E7600 #E7535, #E7350)

For use with NEBNext Multiplex Oligos for Illumina (Unique Dual Index UMI Adaptors DNA Set 1) (NEB #E7395), refer to the Protocols tab for UMI Adaptors-specific guidance. 

Functional Validation

Each set of reagents is functionally validated together through construction and sequencing of a transcriptome library and sequenced on a DNA Library on the Illumina Sequencing Platform,

Lot Control

The lots provided are managed separately and qualified by additional functional validation. Individual reagents undergo standard enzyme activity and quality control assays, and also meet stringent criteria in the additional quality controls listed on each individual component page
This product is related to the following categories:
Library Preparation for Illumina,
DNA Library Prep for Illumina,
RNA Library Prep for Illumina,
This product can be used in the following applications:
NEBNext® Ultra™ II DNA Library Prep

Reagents Supplied

Reagents Supplied

The following reagents are supplied with this product:

NEB # Component Name Component # Stored at (°C) Amount Concentration
  • E7546S     -20    
  • E7546L     -20    

Properties & Usage

Materials Required but not Supplied

Magnetic rack or plate (e.g., NEBNext® Magnetic Separation Rack (NEB #S1515S), Alpaqua ® 96S Super Magnet Plate (#A001322), or equivalent)

Protocols, Manuals & Usage


  1. Protocol for use with NEBNext® Ultra™ II End Repair/dA-Tailing Module (E7546)


The Product Manual includes details for how to use the product, as well as details of its formulation and quality controls.

FAQs & Troubleshooting


  1. There are 3 NEBNext Ligation modules, the NEBNext Ultra II Ligation Module (#E7595), the NEBNext Ultra Ligation Module (#E7445) and the NEBNext Quick Ligation Module(#E6056). Which module should be used in conjuction with the NEBNext Ultra II End Repair/dA-Tailing Module?
  2. How do I clean up the reaction once complete?
  3. Can I store the reaction after it is finished in the thermocycler (ie when it reaches the 4°C hold)?
  4. What do I do if I see a precipitate in the Ultra II End Prep Reaction Buffer?

Quality, Safety & Legal

Quality Assurance Statement

Quality Control tests are performed on each new lot of NEB product to meet the specifications designated for it. Specifications and individual lot data from the tests that are performed for this particular product can be found and downloaded on the Product Specification Sheet, Certificate of Analysis, data card or product manual. Further information regarding NEB product quality can be found here.


The Specification sheet is a document that includes the storage temperature, shelf life and the specifications designated for the product. The following file naming structure is used to name these document files: [Product Number]_[Size]_[Version]

Certificate Of Analysis

The Certificate of Analysis (COA) is a signed document that includes the storage temperature, expiration date and quality controls for an individual lot. The following file naming structure is used to name these document files: [Product Number]_[Size]_[Version]_[Lot Number]

Safety DataSheets

The following is a list of Safety Data Sheet (SDS) that apply to this product to help you use it safely.

Legal and Disclaimers

Products and content are covered by one or more patents, trademarks and/or copyrights owned or controlled by New England Biolabs, Inc (NEB). The use of trademark symbols does not necessarily indicate that the name is trademarked in the country where it is being read; it indicates where the content was originally developed. The use of this product may require the buyer to obtain additional third-party intellectual property rights for certain applications. For more information, please email

This product is intended for research purposes only. This product is not intended to be used for therapeutic or diagnostic purposes in humans or animals.

New England Biolabs (NEB) is committed to practicing ethical science – we believe it is our job as researchers to ask the important questions that when answered will help preserve our quality of life and the world that we live in. However, this research should always be done in safe and ethical manner. Learn more.