Abstract: A system for extracting drill cores from a borehole. The system enables a semi-resilient sleeve-inserted in a housing—to be sealed about the circumference of a drill rod thereby allowing for upward backpressure against the drill core when activated. The system comprises: a housing assembly having sleeve retaining annular rings with edge treatment that forces outward displacement of the central region of the sleeve so as to ensure utmost clearance from a drill rod, which traverses said sleeve. The system thereby allows extraction of drill core samples without the time-consuming fishing method therefore increasing productivity by a substantial margin.