The C18 has a standard Bessell BVRI set of round 2" diameter filters
with thickness of 5mm.
Also it has a round 2" diameter Luminance filter bought from Bader around 2013.


Doron Chelueche purchased a set of 5 Narrow Band filters of-the-shelf from
Asahi at the end of 2013. These are round 2" diameter filters
with thickness of 5mm  labeled, based on the central wavelengths as:
NB4300
NB5200
NB5700
NB6200
NB7000
and their transmission curves are in the file:  NB_C18.pdf


Doron Chelueche purchased a set of 5 SDSS ugriz filters, and 14 Narrow Band
custom-made filters, from Custom Scientific at the beginning of 2018. 
These are mounted 1.25" filters labeled, based on their central wavelengths 
as in the file C18_NBfilters_list.pdf .  The filters thickness is 3mm.
The transmission curves of these filters are in 
C18_NBfilters_transmission.pdf
and the thoretical transmission curves are in 
C18_NBfilters_theoretical_transmission.xls
with an ASCII version of this xls file in
C18_NBfilters_theoretical_transmission.zip