Water Miser's were made for golf cart batteries...........
For a little more $$ why not go "first class" and get one of the Flow Rite systems that incorporate a water filling mechanism with the "sealed" caps.
Seems it was about $125. for 4 six volt batteries.
Hal & Ginny Miller '04 Beaver Santiam PRT40
'04 Saturn Vue - US Gear Brake - Blue Ox tow
4 "girls" (3 Irish Setters - Retriever)