The purpose of the Easy Walk Harness is similar to that of a Gentle Leader. It clips in the front, so that if the dog pulls, it is simply turned around (clipping it on the dog's back defeats the purpose and actually gives the dog MORE leverage to pull).
However, because it is not worn around the muzzle, it is easier for the dog to adjust to wearing it.
I bought the Large for Leo, although it is just slightly too big. Megan has a Medium/Large (available only online) at home, and will bring it in for Leo to wear.
After fitting the harness on Leo, we decided to do a dog-meet, in anticipation of a regular play-date with another Pen Pal named Carl (here's Carl's blog: http://shelterdogbmod.blogspot.com).
The meet went very well -- even though Leo attempted several times to hump Carl, Carl did not seem to mind, and Leo didn't seem to mind when Carl tried to give it back. The two played very roughly, but did seem to wear each other significantly.
Afterwards, Carl went back to his kennel, and we began a review of things Leo knows (sit and down), and things we've been working on (touch and stay). Carl's Pen Pal, Dave, also showed us how to teach "Follow," in which Leo follows a downward-pointing finger in a figure 6, from facing you, to almost behind you, to a heel position.
Tomorrow (Sunday, 1/31/2010) will be a fun day for Leo. We are attempting another off-site trip, to Central Bark Doggie Day Care. They have graciously offered to open their doors to ACCT Pen Pals for some off-leash (indoor!) fun!