Gregdry, that's probably primer sealant.
I remember when CTD was just a table at the local gun shows selling army surplus and cheap accessories. I deal with the store here in Ft. Worth and find them to be very well stocked & professional. I have also mail ordered from them on a few occasions and recieved good results.
If you're looking for high end equipment I'd look elsewhere but for good stuff at good prices they are as good as any.