I got the small-medium size NO SIT HAUNCH HOLDER DOG GROOMING RESTRAINT and it doesn't fit properly on either of my dogs. I have a 10 lb (12" long) and 13 lb (13.5" long) Yorkie Mix and the neck loop is perfect, but the loop that goes around the abdomen is too long....which means they can still sit down. Maybe if my dogs were longer this might work. (I took a picture of my 13 lb dog to show you.)
As for the "secure hold," that's a joke!! It's a plastic tab that you're supposed to pinch in the middle so that you can slide up and down then release it and it's supposed to stay; however, it goes up and down whether or not you squeeze the middle of it. I guess that's not really a problem if you have the arm on the grooming table up high enough so that there's no chance of the dog slipping out of the loop.
NEW! No-Sit Haunch Holder. Adjustable to fit small and medium sized dogs. Easy adjustment, squeeze and slide adjustment tabs - secure hold. Quality durable covering over cable to protect dog's neck and abdominal area. Brand: Downtown Pet Supply.