This part of ISO 15835 specifies requirements for reinforcement couplers, hereafter called couplers, to be used for splicing of steel reinforcing bars. This part of ISO 15835 specifies requirements for couplers to be used for mechanical splices in reinforced concrete structures under predominantly static loads and additional requirements for couplers to be used in structures subject to high cycle elastic fatigue loading and/or to low cycle elastic-plastic reverse loading. This part of ISO 15835 is intended to be applicable in relation to the various reinforced concrete design standards as well as in relation to the various standards for steel reinforcing bars. This part of ISO 15835 also provides directions for the evaluation of conformity of couplers. Compression-only couplers such as end-bearing sleeves are not covered by this part of ISO 15835.