I have been experimenting for some years with different ypes of razor blades and shaving creams to get a smooth shave, without a rash or pain. I ended up with a four bladed Shick that I could use against the grain of the beard to get the shortest and smoothest shave possible. The part below the jaw and below the chin was still not smooth.

And then I bought this coolskin shaver,
I use it by washing my face fist, then I apply a very thin layer of Nivea shaving gel (about a pea size of gel) an then I start shaving. Every now and then I just wet the blades in the water to get rid of the foam and I wet my face regularly with my left hand and after I have finished You can still feel beard at the difficult places while wet), I dry my face and click open the blades and rinse then under the tap. When using I can press the gel button to get that extra bit of gel when needed.

When dry my skin overall is shorter (smoother) than with the blades.
I still have a very faint rash after about a week at the beard's ed in my neck, but not painful. The charged battery life last longer than an hour and charge in about the same.

In hot weather I do not get a rash any more and I will recommend this shaver over and over again.

I see you can use it under the shower as well, but I have not tested it yet.