EN3. The dormakaba (formerly known as Dorma) BTS80 Floor-Concealed Spring Door Closer offers adaptability to almost any installation. Thanks to the closer's compact body, the BTS80 can be used where larger closers would be prohibitive. A wide selection of interchangeable spindles, together with its compact design make the BTS80 suitable for virtually any floor covering or threshold application.. Hold open hydraulically adjustable. Suitable for most applications. Concealed installation. Non-handed for single and double-acting doors