Generally, they are considered part of percussion.
sleigh with bells
The Orchestral Tubular Bells was created on 1975-08-28.
sleigh bells is noun
Sleigh bells are a kind of bells however there's also another definition for "sleigh bells" there also known as an American noise pop music duo.
sleigh bells, jingle bells
There are many places where one could purchase sleigh bells as a Christmas decoration. One could purchase sleigh bells at Amazon, Walmart, Target, and Kmart.
Merry Sleigh Bells - 1898 was released on: USA: January 1898
they represent the bells on santa's sleigh an reindeer
a "one horse, open sleigh".
Santa Claus
Ye Merry Sleigh Bells - 1897 was released on: USA: January 1897
It is two words. The only exception would be if the term was used as an adjective (e.g. a sleigh-bell sound).