These attachments will fit on nearly all cable-based weight machines - cable crossover, lat pulldown, row and more. The carabiner you should already have at the end of the cable will clip into the metal ring on these attachments.
These lat bars will fit on any cable machine in the gym such as a lat machine or cable crossover machine. A lat bar is a special bar that you can grip anywhere along its length for narrow or wide grip pulldowns while sitting on a bench. Many lat bars have a swiveled attachment to keep the bar facing the right direction during the lift as you bring the bar to your chest or even push it down to your waist.
Tricep pressdown bars have two grips with palms in a neutral (palms facing each other), pronated (palms facing down) or semi-pronated position. There isn't necessarily one best attachment or hand position. It depends on individual preference.