diff --git a/README.md b/README.md
index b0db9d0..c2b3ed1 100644
--- a/README.md
+++ b/README.md
@@ -30,6 +30,14 @@ the standard Docker installation.
 Once you can run the [`hello-world` image][docker-helloworld] you're ready to
 start!
 
+## What does Docker build
+
+Docker will produce two files in the `zips` directory:
+1. The main ROM zip file e.g. `lineage-20.0-20230702-microG-<device-name>.zip`. This file can be flashed from recovery as described in the next section.
+2. A `-img.zip` file e.g. `lineage-20.0-20230702-microG-<device-name>-img.zip`, that can usually be flashed using up-to-date versions of `fastboot`.
+
+(Note that the process of flashing using `fastboot` is not documented, is untested, and is done ***at your own risk***.)
+
 ## How can I build LineageOS?
 
 This Docker image contains a great number of settings, to allow you to fully
@@ -74,7 +82,7 @@ official lineageos4microg builds. To include it in your build, create an XML
 
 If you wish to add other apps to your ROM, you can include a repository with
 source code or prebuilt APKs. For prebuilt apks, see the [android_vendor_partner_gms][android_vendor_partner_gms]
-repository for examples on how the `Android.mk` file should look like. 
+repository for examples on how the `Android.mk` file should look like.
 
 Include the repo with another manifest file like this: