A pipetter is disclosed that has a suction lumen with an opening and an ejection bar that slides relative to the suction lumen. The pipette tip has a distal end opening and a proximal end with a rim. The pipette tip has a pipette wall with a low-force stretch region with a plurality of thinning channels. The system comprises at least three configurations: an insertion configuration, wherein (1) the suction lumen is inserted into the proximal opening, and (2) the ejection bar does not abut the rim; a sealed/installed configuration, wherein (1) the suction lumen forms a liquid-tight seal between the suction lumen and the pipette wall, and (2) the ejection bar abuts the rim, preventing further insertion of the suction lumen (