Hasco SF1200 extension wrench made of chrome vanadium steel, a tool that combines durability and reliability. - Brand: Hasco - Model: SF1200 - Type: Extension Wrench - Material: Chrome Vanadium Steel Thank you for viewing. This wrench can be used to extend box wrenches, spanners, etc. It provides a better grip than extension pipes and is designed to make it easier to apply force. I used it for about 3 months, and it was a really good product. Selling at a bargain price.