Scratcher 3 : A device fastened to casing which aids in removal of mud cake from the annulus while the pipe is being moved during the cementing operation. (Bul 10C)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}