There is, but, due to shoes being more prevalent than boots, a
boot tree is a niche item that is rarely stocked by wholesale traders.
The boot tree does come in two configurations,
- Ankle high boot trees
- Knee high boot trees
You could possible classify the above image for knee high boots
as a "shaper" or "stretcher" rather than a boot
tree, but, they are commonly referred to, and, sold as, boot trees.
The problem with a shoe, or, a boot tree, is that, in an ideal world
they need to be custom designed for the boot or shoe in question.
The downside with a boot tree which isn't custom designed - therefore
ill fitting - is that it will have it's work cut out to stretch
the boots sole. Custom designed boot tree's can cost upwards of