Enternal Nutrition Question!!

Ok, I am a student and trying to learn about all the different types of tubes and have confused myself further. Has anyone heard of duotube? This is what our hospital uses. Is it the same as a dobhoff? Also, what would a 6 fr, 15" tube be used for? Peds maybe? It doesn't not look like a j tube I don't think......

Can anyone reccommend any good sites that actually show pictures of what all the different types look like?

Also, any tips on med admin.? Do you flush before and after when the automatic flush system is in use?

Thanks! Any advise would be great!