Is it difficult to fasten or release the wire from an electric fence T-post? Here is your answer! These American FarmWorks Pinlock T-Post Insulators for 1.25 and 1.33 in. Studded T-Posts have molded pins that hold the wire tightly. When you want to release the wire, just pull the pin! Heavy-duty flanges hold the electric fence insulators securely to 1.25 in. and 1.33 in. T-posts. For durability, the black pin-lock T-post insulators are made of top-grade UV-stabilized polyethylene that prevents arcing and provides long life. You can use these versatile electric fence post insulators with polywire, polyrope, steel and aluminum wire.