The Federal hazardous materials transportation law requires the Secretary of Transportation to ensure that, to the extent practicable, regulations governing the transportation of hazardous materials in commerce are consistent with standards adopted by international authorities (49 U.S.C. 5120(b)). Harmonization enhances safety, facilitates compliance, and improves the efficiency of the global transportation system by minimizing the regulatory burden on the public thus promoting trade. After a thorough review of the provisions recently adopted by various international regulatory bodies, PHMSA has identified areas in the Hazardous Materials Regulations (HMR) in which harmonization with international regulations will provide an enhanced level of safety, an economic benefit, or in many instances both increased safety and economic benefits. As a result, this rulemaking would amend the HMR, where appropriate, to maintain alignment with international standards that become effective as of January 1, 2025, and consequently facilitate the safe global trade of hazardous materials. Proposals in this rulemaking action may include but are not limited to: new entries and provisions for battery-powered vehicles (sodium-ion, lithium metal, and lithium ion); new classification provisions for certain fire suppression devices; amendments to limited quantities for Division 2.2 gases; and updates of International Organization for Standardization cylinder manufacturing and testing standards incorporated by reference.