In order to purchase SignLens Basic, you will need to install the Apple Books app on your Mac, iPad, or iPhone.
Apple Books App
Launch the Apple Books app and click on search. Enter “SignLens Basic” or click this direct link.
Apple Books on MacOS
Apple Books on iOS
Tap on the Buy/$19.99 button to purchase. Authenticate with Face ID, Touch ID, or your Apple ID password and the book will begin to download.
Once your purchase is complete, you can view this interactive ebook on the Apple Books app. Simply open the app, click on Library and tap the book to open.