The BT -Spannschloss (turnbuckle) is part of an easy to use connection system - without additional materials and tools. The BT-Spannschloss (turnbuckle) enables efficient and precise assembly and durable connections for precast concrete elements. by using BT-Spannschloss and corresponding connection materials, precast elements can be joined together without using mineral grouting. This means no curing or standstill times due to low temperatures. The BT- Spannschloss can be fully loaded straight away. The building inspection approval (Z-14.4-599) certifies the reliability of the product. The BT-Spannschloss is offered in three sizes - M12, M16 and M20 - and is available in galvanised or stainless steel.