Just to add to Jay's comments above...
The 9V battery power (on the LA and Morley PW or Volume II) is for the adjustment in 'level' bleed through (which in itself doesn't take too much power but the universal 9V will do it just fine and is the 'norm' to using it.
I opted for the LA (got in trade otherwise would've bought the non endorsed Morley one...for much cheaper) specifically because of the size it takes up on my
pedal board.
The ernie ball I'll admit was smoother and had a nicer roll..but..space is a commodity to me on my board....
my foot learned to adjust just well.
and the volume bleed adjustment is a handy feature to use every now and then.
my 2 cents.