Here are some possibilities and why they might be confused:
* Beaver Tail Casters: This is a type of caster (a wheel attached to a swivel) used in furniture or industrial applications. The name comes from the shape of the caster, which resembles a beaver's tail.
* Beaver Dam Casters: This could refer to a type of caster used specifically for building dams or other structures related to beavers, though this is not a common term.
* Misunderstanding: You might be thinking of something else entirely, and the term "beaver casters" is just a misunderstanding.
To help me understand what you're looking for, could you please:
* Provide more context: Where did you hear this term? What were you reading or discussing when it came up?
* Describe the context: What is the item or situation you're trying to understand?
With more information, I can hopefully give you a more accurate answer.