Redi-base makes a variety of bases including a couple kinds of beef, but I’ve been using just the plain-labled “beef” base for years and it’s excellent.  It has a nice natural beef flavor,(not artificial tasting, or with an aftertaste as I find other beef bases have).   I don’t think it’s low-sodium, but don’t find it overly salty.  To me, Redi base’s chicken base is not that special, and I use either Swanson organic chicken stock, or Better than Boullion.  I like the new Swanson chicken boost packets for when you need a small amount, I haven’t tried their beef flavor.