The rigid plastic blades are perfect at routine algae removal from aquarium glass. They are also surprisingly efficient at removing newly formed coralline algae from glass.
The longer 86mm blades are very good for general purpose algae removal, and provide a generous cleaning capacity ensuring that your routine glass cleaning does not take all day.
By replacing a long blade with a shorter 45mm blade on one end, the cleaner becomes multipurpose. The magnetic attraction increases dramatically and allows you to clean the more stubborn algae with the shorter end.
If however, you really need to scrub away at newly formed coralline algae, or neglected green algae, use a short blade on each end.
The magnetic attraction will be zeroed in on the two small blades and ensure the offending algae is removed.
Tunze have gone further. Not content for you to rely on their plastic blades alone, they have also included stainless steel blades. These are for algae which you cannot remove by using the plastic blades with all the will in the world. The stainless steel blades are also rounded at the edges.