Not positive, but I think it refers to the smaller spacing of 2x4" that horses can't get their feet into. I watched a neighbor's lab climb my no-climb Red Brand horse fencing and when he got to the top, his face hit the electric wire I ran a few inches above the woven wire. YIPEYIPEYIPEYIPEYIPE!!!! All four of his feet were grounded on the metal fencing, so he REALLY got zapped!
For goats, the smaller spacing also prevents them from sticking their heads through it and becoming vulnerable to a rumen-rupturing bonk from another goat.
eta: Thanks, Pat, you confirmed it before I finished typing!
When you put up the 4 by 4 fencing, is it just the fencing or is it wired to electricity? I have two Oberhasli's and a Nubian/Alpine cross and Im looking for some fencing that can be taken down and moved fairly easy? I want them to eat the brush around the house without letting them loose or staking them. Does anyone let thier goats free roam when they are home and working around the yard? Mine seem to stay right with me most of the time. They follow me like dogs..lol
Kathie