• The Acme 18A Staple Gun With Bottom‑Load Magazine, model 654018B 

• It features a jam‑less design, bottom‑load magazine, and works with a 3/16‑inch crown. 

• It also interchanges with Arrow’s T‑18 staple model. Accepts staple leg lengths of 3/8", 7/16", and 1/2". 

So this is a specialized wire & cable / crown staple gun more than a generic home/office staple gun.