They don't fit automotive style batteries. Your caps must be bayonet type ... Whatever that means?
Hydrocaps are catalytic. Gadgets like that have been around for a long time, I remember German ones (Hagen I think) in the 70s and they weren't new then.
Most people find them not very good, inadequate capacity and the catalyst gets poisoned quite quickly.
The water miser ones appear just to be baffles.
Most batteries since about the same time have had caps that you can leave in while boost charging and that will stop spray and many of them include a flame arresting porous disc - ceramic or sintered PVC - that avoids any risk of flashback and explosion within a cell. (It became possible because of lower gassing rates from improved materials - low antimony or calcium content.)
I once had to inspect a 48V 2000Ah telephone exchange battery where someone had dropped a spanner on the busbars while boost charging with the vent plugs out (against our instructions but traditional habits die hard). The spanner melted and sparked, the gas flashed and some cells exploded. There were shards of 1/2" thick SAN stuck in the ceiling. He was lucky just to have minor acid burns.
So if you have flame retardant vent plugs, do leave them in!
I don't know what batteries you (Conachair) have but be sure your standard vent plugs are unsatisfactory before spending money on these!
on the basis water loss is by electrolysis where it is turned into h2 and o2 i dont see how baffles will recombine the loss of cell water.
Escaping gases, exiting through the moisture-return medium during the charging cycle, carry fewer electrolyte laden droplets, assuring that cell electrolyte gravities are better maintained.
I have US battery 2200 which I believe are identical to trojan T105's. With a sort of 3 way cam cap thing. Thinking it might be worth it just for the lift up filler caps, the caps on at the moment are a bit messy for filling and checking SG.
this..
http://www.altestore.com/store/Deep...Miser-Vent-Cap-Reduces-Battery-Watering/p535/
..says they have sintered discs.
Ta
They don't.
Which does sound like pure advertising but on some other forums people who have fitted them seem to be on the whole positive, so I might give them a go. They cost next to nothing and if it keeps the bettery a little drier on top them it will be worth it.