The belly strap means she can't escape, and those of you with similarly adventurous terrierists will understand what an advantage that lift handle on the back is going to be: Mollie has a nasty tendency to jump over 2ft high walls and then discover they're that bit higher on the other side. Most of the time, she can jump back, as she's quite agile and bouncy - but every now and then she gets stuck.
The harness is also breathable, lightweight and can go in water without soaking a load up, so we don't have to take it off and carry it round just cos she's jumped in a lake... which is good.
She hasn't worn it out and about yet, as it only arrived yesterday, but as you can see she seems quite happy with it - we were out playing ball with her wearing it and she was happily leaping about, over the fence, over the hedge, doing her usual spectacular mid-air catches.
I'll report back on how the harness fares when we're out and about, but since it was designed with search and rescue dogs in mind I'm guessing it'll last us for a few years.
It's a Ruffwear Web Master. I got this one cheap as an end of range, but the new one has a broad chest pad, is generally a bit sturdier, and has reflective stripes and longer sleeves on the straps.