SigmaPlayer2 is an Android app developed by BUN-EIDO PUBLISHING CO. LTD, which contains listening materials accompanying the textbooks published by BunEido. This app eliminates the need for CD players for listening practice and allows users to listen to audio content, such as English conversations, at their convenience. The app also provides an option to adjust the speed of the content. With SigmaPlayer2, listening practice becomes more accessible and convenient.

Moreover, SigmaPlayer2 offers an additional feature that allows users to customize the order of audio playback for some English vocabulary books. This feature is helpful for learners who want to focus on specific words or phrases. Overall, SigmaPlayer2 is an excellent app for anyone who wants to improve their listening skills and learn English more effectively.