Don’t confuse this with standard PVC tubing!
As many of you know, the practice of putting an outer jacket on the mono loop is not new. It has been done in the past (mainly in Europe) using PVC tubing. The reason this did not catch on in the USA was because it was just that, PVC tubing, and offered no protection for the mono that it was intended to protect. Now, fast forward to today’s technological advances in thermoplastic elastomers and we now have a flexible tubing to provide added protection for your mono loop.
The MAKO Spearguns Mono Jacket is specifically designed for use with high profile sharkfin tabs with pre drilled mono holes. Although the holes in the sharkfin tabs are filed smooth, the sharkfin tabs are thinner than the diameter of the spear. By putting this outer jacket on the mono (where it goes through the sharkfin), it will extend the life of the mono and reduce the possibility of breakage when passing through bones or gill plates.
Sold by the Foot.
This stuff is awesome!! 
Mono jacket