Telecom/ITE standard UL60950 requires Reinforced insulation between a 120v primary circuit and a TNV circuit (POTS is TNV3). Reinforced insulation requires a distance through insualtion of 0.4mm. I think the protective sleeve just ensures this .4mm requirement is met without relying on the existing phone wiring - probably a good idea.

One thing that really caught my eye was the statement, "This product is compliant with UL 1863, UL 60950, FCC part 15 Sub-part B class B and FCC part 68". "Is compliant" could be taken to mean "listed to"...or not. I know from experience with one NRTL, there are certain types of products that the particular NRTL (that shall remain nameless) will not give a listing to, even though the product may meet all applicable safety requirements. Some things just make some people too nervous.

OK, somone buy one of these so we can check it out! Just kidding, but I would be curious to see if it has any safety/NRTL marks. If it was submitted for TIA/EIA/IS-968 (formerly FCC part 68) then there should be a traceable ID number on the product somewhere.

Neat product though.