This is the Army Painter AW2005 Warpaints Air Gloss Varnish 100ml Acrylic.

The Army Painter Airbrush Varnishes are non-toxic, water-based acrylic varnishes designed for use with the airbrush. 

Formulated to ensure a smooth and even coat when applied through an airbrush, these varnishes protect your miniatures from chipping and wear and tear. 

Key Features:
High-quality acrylic airbrush varnish
Protects your miniatures from chipping
Non-toxic and water-based

Airbrush Varnishes comes in spill-proof 100 ml./3.3 fl.oz. dropper bottles for easy dosage.