Note that there's a very wide range of reflective performance among the different types of tape. The V82 is very high-performance prismatic tape, nearly up to the level of 3M Diamond Grade but far thinner so it doesn't peel itself off curved surfaces. Basic glass-bead tape is still better than nothing, but I prefer to use the V82.

Here's a reduced-light photo showing V82 verus 3M's cheap glass-bead stuff:



And here's more on the various classes of tape: http://www.trafficsign.us/signsheet.html