Most caulking guns bend in heavy use, so the ratchet advance and plunger don’t work properly. Ours has a top-strap to keep it aligned, and it’s driven by a unique friction system that handles tremendous pressure. Easy to clean, too. Made of steel and zinc castings. All parts are plated or painted to resist rust or corrosion. Costs a little more than hardware store types, but you’ll never have to buy another. 20 ozs.