It's basically fool proof , just don't use massive amounts of air and be patient with it,....the kits have different size needles for whatever animal your doing .

It's very quick effective way if done right.

Anybody hear of houndman. Named " Donnie Clifton" out of Ranger, Texas...he runs a pen I think its called " grandpa's pen"...I like to get his contact info if anyone has it. Thx