What is Speedskim SF & PF?

"For fine finishing and drywall. Perfectly balanced, the blades close material in leaving it ideal for top coats and finishing plasters. Compatible with all gypsum based finishing plasters (hand and spray applied), jointing systems and compounds. Simply changing the angle of use (21 degrees recommended for flattening and finishing), to approx. 70 degrees recommended for ‘ruling off’, the Speedskim ST blade becomes inherently more rigid. In changing the angle of your Speedskim to be more perpendicular to the substrate, the blade distributes backing plasters and renders (including insulated renders) with ease. "