Android application package with the generic name base.apk and a size of 15.3 MB. The name is uninformative and gives no app title, version or developer, so its purpose cannot be told from the listing. Base.apk is the default name Android gives an installed app's main package when it is extracted from a phone. Repair shops often keep such tools for boardview viewing or diagnostics. Scan it for malware and inspect the package name and signature with an APK analyzer before installing it on any device.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @esquemaseletricos. Enginerys does not host this file.