How many covers are usually needed?
I put 1 on each regulator hose I have 2.
i couldn't get mine on, even with warming it in hot water
Depends on how many hoses you want to protect on your regulator.
I used one cover on each of the hoses coming out of my primary regulator. At my primary was where I used these and where other hoses had worn because I did not have any protection there. For myself, the cost of this hose protector is much cheaper than a new hose.
Use 1 for each uncovered hose on the regulator. Most regulators have 4 hoses (your breather hose, buddy breather hose, BC inflater hose, and guage hose) the inflater hose was short and did not need a protective cover since there was not much stress or bending. My breather hose had a cover supplied by the manufacturer (Oceanic). I put a protective cover on the buddy breather hose and the guage hose. These attach up at the regulator. My wife and I have same regs, easy to spot the difference now - I used black on mine and blue on hers. Works pretty good and easy to install (if tight fit, soak in hot water for a couple minutes - makes it a bit more stretchable)
I have one for the first stage end of each hose in my setup. So in my case 3, one for the primary regulator, one for the octo and one for the BCD inflator hose. I don't have a high pressure hose since I use a wireless transmitter.
Note the secret to putting these on is to unscrew the hose from the first stage then after having soaked the protector in hot water (like cup of coffee hot) for 2 minutes or so to soften them up then slide them over the hose. then reattach the hose to the first stage.
I would say four ......but it depends how many hoses you have on your first stage. Hope that helps you out.
you need one hose protector per hose
installed on the end that goes to the first stage
you use one for each hose where it attaches to the first stage of the regulator.