COVERAGE - A 25KG Bag & 5L Bottle kit covers 4.8m2 at a thickness of 3mm. STOPGAP 200 is a rapid drying, two component, low odour acrylic, self-levelling smoothing underlayment suitable for use in light to heavy-duty applications for preparing sound absorbent and non-absorbent subfloors prior to the installation of new floorcoverings.