You are downloading the Tetra Lockscreen XAP file v18.104.22.168 for Windows Phone. Tetra Lockscreen is a free and useful Productivity app: Tetra Lockscreen, a Microsoft Garage project, brings functionality to the forefront of your Windows Phone 8.1 device. Focused on fast, fluid, and ... You can now download the offline XAP file to install & try it.
Download Locations for Tetra Lockscreen 22.214.171.124 XAP file
Note: To install it manually from an SD card, you should choose one of the server location above to get the offline Tetra Lockscreen XAP file, move the file to your phone's SD card and then tap 'Install local apps' in the phone's App list.