Each turret, hull and module with protections can be upgraded. Thanks to Micro-upgrades, you don't need to wait until the next modification of an item becomes available, you can improve its stats step by step immediately.
When fully micro-upgraded, M0, M1 and M2 modifications of turrets, hulls and modules have equal parameters to their higher modifications. When you fully micro-upgrade an item, you will be able to get the next modification for free, if you have the required rank for that modification.
In order to start this process, you need to select an item in your garage and click on the "Upgrade" button. One item can have several parameters that can be upgraded all together. For both turrets and hulls, there are 10 upgrade steps for M0, M1, and M2, while M3 has 20 upgrade steps. Once the process of upgrading has started, installing the upgrade will take some time. However, you can always skip this waiting time by clicking on the "Speed up" button. Alternatively, equipment can still be used while the upgrade is in progress.