The Brush 'n Grow Ponies were first introduced in Year 6 of the My Little Pony line. With multicolored manes and tails, the Brush 'n Grow Ponies were all about hair.
Pulling on their tails would make them "grow" longer, while turning the pony's head from side to side would retract the tail back inside the pony's body to shorten it. Their manes were extra long and thick.
The Brush 'n Grow line included earth ponies, pegasus ponies, and unicorns. Each pony came with ribbons, barrettes, and a brush for hair styling. The ponies' symbols were themed around hair accessories.
In Year 7, another set of Brush 'n Grow Ponies was released, this time as Princess Brush 'n Grow Ponies. The Princess Brush 'n Grow Ponies had tinsel in their manes similar to the Princess Ponies line, but had a raised jewel on their foreheads instead of a raised jewel symbol.