'Made by Parks Medical Electronics of USA. Enables close acoustic monitoring of blood flow of conscious patients and during anaesthesia. With the addition of a sphygmomanometer and inflatable cuffs, accurate, non-invasive monitoring of blood pressure can occur. Supplied complete with one probe (standard size), One bottle of coupling gel, 240 volt transformer and operator''s manual. The 811B has rechargeable internal batteries for cordless operation. The 811BL model has the addition of cautery suppression to allow uninterrupted performance during cautery use. Note: The Doppler probe has a finite life. Always treat with care, and remove any gel with a damp swab or similar after use.