Conmed Disposable Non-sterile Pencil Sheaths, Box or Case, 7-796-18. Disposable, clear plastic Hyfrecator pencil sheaths protect the pencil body from external contamination during procedures. 8" (20.0cm) long. Comes in a box of 100 or case of 12 boxes(1200 sheaths. The Sterile Sheath is a convenient and economical way to maintain a sterile field while using the Hyfrecator electrosurgical reusable pencils. The sheath is designed to fit over both Hyfrecator and other handheld instruments. The extra sheath length allows the instrument to be placed within the sterile field. A non-sterile sheath is also available. Employed use of sheaths promotes pencil longevity, speeds changeover from patient to patient, and prevents.