In the past, I have been using Thousand Oaks Solar filter which does not work so good when it comes to high resolution viewing of the Sun.
Thousand Oaks filter is made of glass and is an off axis filter. C14 telescope is too big to have a full aperture front solar filter because although solar filters drop the sunlight and solar heat way down, still in a big aperture telescope like C14, the amount of heat would generate too much temperature instability which will degenerate the solar views. That is the reason, probably no one makes a full aperture front plate solar filter as big as C14 can use.
Unlike Thousand Oaks, Astrozap uses solar film in their filters. Solar film filters have an advantage over glass filters when it comes to high resolution viewing and imaging of solar surface granulation. Though glass is much more durable than a film. It's hard to take care of solar film filters. But film can easily be replaced with a new one; these are not so expensive.
So the new upgrade is of the New Astrozap Film Filter for my C14 telescope! The off axis filter makes C14 essentially a 6 inch refractor scope. With the central obstruction of the secondary mirror gone from the view, this scope can provide very high resolution of the sun's surface.
In the image, you can see Astrozap white light Solar Filter attached on the front Schmidt plate of C14.