hengli was established in 1972 to specialise in the development of a wide range of innovative spirit level designs. ???Over the years the company has refined manufacturing techniques to enable us to produce a range of quality spirit level vials - the heart of an accurate levelling instrument. ???hengli plant are the ones to trust for accuracy. They are manufactured to exacting standards to maximize durability, dependability and precision. Find the level vial product you're looking for within the following categories??e stock a wide range of tubular, circular and acrylic block vials. Other sizes are available, so if those listed below do not suit your application, then please contact us. We are here to help! the products include Products list