The keyword "portable" is crucial here. The physical copy of Shiv Sahastra Naam published by Gita Press is a small booklet (usually 48 pages). However, carrying a physical book isn't always convenient in modern life.
Gita Press has two main publications containing the Shiva Sahasranama. For portability, look for the : shiv sahastra naam gita press pdf portable
Chanting the Sahasranama is believed to provide immense spiritual and practical benefits: The keyword "portable" is crucial here
Upamanyu explained that these names were originally composed by shiv sahastra naam gita press pdf portable