The wideband gene is not discussed often and when it is, it is often confused with the nonextension gene (e), probably because it has a similar effect and the two are usually ‘used’ together.  

The wideband gene has two alleles.  W is dominant, so Ww and WW both produce the normal colors.  The ww genotype doubles the width of the ‘red’ bands in agouti rabbits.  

The wideband allele is most common in non-extension rabbits (reds - A-eeww and torts aaeeww), where it helps to reduce smut and intensify the red color.  It is also common in coppers - along with high rufus factor it helps to distinguish the copper from the chestnut agouti.

In chinchilla rabbits (A-chd-ww), the wideband gene doubles the width of the silver-white bands, resulting in rabbits that are lighter and less even than normal.  In other agouti rabbits (A---ww) the bands are also wider and the red shade may be more intense as well.  In general, wideband is accepted but not preferred in the chinchilla and other agoutis.   Since the selfs and tans don’t have bands, the wideband effect is not seen, and is just carried.