The magnetic sorbent «ExtraGen® SPRI» presents a water suspension of silica-coated iron oxide particles with immobilized carboxylic groups. This material is intended for size-selective isolation of nucleic acids fragments from clinical and biological samples. The magnetic sorbent water suspension possesses «intermediate» sedimentation stability, important for the use of the material with automatic stations for DNA isolation. The most effective DNA size-selectivity was achieved through protocol and buffer solution optimization. As the tests had shown, depending on the conditions ExtraGen® SPRI is able to separate DNA frogments from 50 to 1200 bp. This material can be used for DNA library preparation in next-generation sequencing, PCR products purification and other molecular biology applications.