suppliers of some cheap refractors supply a welder's
glass filter (pictured left) that screws on to the eyepiece.
DO NOT USE THESE!
heat up and crack as you are looking through the telescope.A
proper solar filter always goes on the front end
of the telescope, blocking the sunlight before
it enters the optical system.
Thanks to the Orion
Telescope Center for the loan of this unsafe filter.
Orion does not sell these! They just had one around
as a bad example... They are good and knowledgable people.