The rim tapes you can find easily in shops are durable, reliable, sturdy but unfortunately "very" heavy.
Rim tape is among spinning elements of the bike, so it’s twice useful to make it lighter when you’re looking for gramms saved.
The weight save realized while switching from a normal rim tape to a very light one isn’t huge since it’s only around 15 gramms but it represents a dynamical gain of 1.44 g.m² (mR²).
As example, on a light rear wheel using for example a flat 360gr rim, 28 spokes weighting 4.8gr each, 0.3gr alloy nipples and a 170gr clincher coupled with a 55gr air tube, the dynamical gain is slightly over 2% so 4% for a wheelset. It means that the wheel resistance to speed changes (accelerations or decelerations) will be decreased of 4%. On a bike and its rider it’s negligible but still, it’s interesting to do it to make races (especially criteriums) easier.
NB: hubs play almost no role in momentum of inertia of a wheel, we do consider them as negligible. You can download this Excel sheet representing what is explained just before.(with a different example).
So I looked for the lightest rim tapes I could find. After a few searches, Rox rim tapes seemed to be the lightest ones. Unfortunately they are almost not sold in Europe. I had to ask Fairwheelbikes to get some.
A Rox roll is enough for several wheels, the weight for one wheel is about 3 or 4 gramms while it’s 18 gramms for a classic Michelin rim tape.