2024 30 CFR 57.20032 – Two-way communication equipment for underground operations

2023 30 CFR 57.20032 – Two-way communication equipment for underground operations

2022 30 CFR 57.20032 – Two-way communication equipment for underground operations

2021 30 CFR 57.20032 – Two-way communication equipment for underground operations

2020 30 CFR 57.20032 – Two-way communication equipment for underground operations

2019 30 CFR 57.20032 – Two-way communication equipment for underground operations

2016 30 CFR 57.20032 – Two-way communication equipment for underground operations

2015 30 CFR 57.20032 – Two-way communication equipment for underground operations

2014 30 CFR 57.20032 – Two-way communication equipment for underground operations

2010 30 CFR 57.20032 – Two-way communication equipment for underground operations

2009 30 CFR 57.20032 – Two-way communication equipment for underground operations