They are ideal for tough scrubbing around raised shapes. Class 10 (ISO Class 4) processing gives you low ionic, nonvolatile residue and particle contaminants. Aqua-Prime process available on all sealed polyester swabs. Coventry exceptionally clean swab produced by Coventry's proprietary process of forming and welding the swab head without the use of adhesives. Featuring either knit or nonwoven fabric heads, these swabs are acid and solvent resistant. Sealed edges build in high strength with no loose fibers or particulates. Coventry sealed polyester swabs have the strongest seams available and will not split.