When it comes to free-hand decorative concrete engraving, touching up, removing islands, voids, and adding extra details to the engraved pattern, the Mini-Mochton Stylus Wasp Concrete Engraver is a handy pneumatic tool. The Wasp’s name comes from its design--it has a single reciprocating carbide stylus cutter, called a "Stinger". Air compressor required (1CFM at 90PSI)