Item Package Quantity is 4pc's-20pc’s. The Stainless Steel Threads are 1/4-20 x 1/2" in length. Thumb Screws have a 1” Round Knob. The Knob is made of Delrin. Thread Material – Stainless Steel - anti-rust and anti-corrosion, strong and durable. These Thumb Screws come in many different lengths. If you don’t see what you need, ask through the Amazon contact seller page and I will list your requirements if not already listed.