Strep-TactinXT 4Flow Starter Kit contains all essential reagents required for purification and detection of Strep-tagII and Twin-Strep-tag fusion proteins. It provides a Strep-TactinXT 4Flow column, Buffer W, Buffer BXT, and Buffer XT-R for purification as well as Strep-Tactin HRP for subsequent western blot detection. Strep-TactinXT 4Flow columns contain a 4% agarose coupled with the streptavidin variant Strep-TactinXT. Due to the broad pH compatibility, excellent pressure stability, outstanding target purity (> 95%), and highest binding affinity, the resin is recommended for all protein classes, especially for low abundant or challenging proteins. The low concentrated agarose enables the simple attachment of larger proteins to the stationary phase, making it particularly suitable for purification of high-molecular-weight targets. In addition, Strep-TactinXT 4Flow allows the application of denaturing agents such as urea.