I got Mocha the regular Puppia harness and returned it for the vest style with the velcro closure at the back. He's 3lbs and I got the XS. With the regular one, it was really hard getting it off him. He has a relatively small neck compared to his head, so it was hard getting it to go over his head when I had to take it off. I had to hold it still while he pulled back to get the harness off and I was worried he might hurt his neck that way. Also, when he had it on, he was usually able to get one of his front legs out of it and into the neck hole. The neck hole was more than roomy in the neck area, but it wouldn't go over his head nicely
I like the Puppia vest harness much better. No stress on his neck when taking it off, and he's not able to get any arms out. I think the regular style harness is good if they have a wider neck, but if they have tiny, fragile necks, I wouldn't recommend it.