A flexible lubricous sheath which covers {HEAD ~ at least a distal portion} of the flexible coil of {TAIL ~ the instrument} is provided with either contrasting colored stripes or palpable ridges, or both, which are located a predetermined distance from the distal end of the instrument 
A flexible lubricous sheath which covers { HEAD ~ at least a distal portion } of the flexible coil of { TAIL ~ the instrument } is provided with either contrasting colored stripes or palpable ridges , or both , which are located a predetermined distance from the distal end of the instrument
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH