The 205 series delivers 2.5 ml per stroke — a middle dosage for body lotion, hair oil and gel cleansers that are too thick for a 2.0 ml pump. The outer-spring layout keeps the metal spring outside the product channel, which matters for formulas with active ingredients or a low pH. The wide 24 mm or 28 mm collar seats on standard PET and HDPE bottles, and the piston chamber is sized for medium-viscosity liquids so priming takes only two or three strokes.