L45 Roller Blind Tube: How to Identify It & Which Motors Fit

L45 is one of the best examples of why roller blind motors should never be selected from outside diameter alone. It is a true 45mm tube, but it is not an Acmeda S45. The internal shape is different, so the crown and drive parts used to connect a motor to the tube are different too.

How to identify an L45 tube

Measure the bare aluminium tube at about 45mm outside diameter, then inspect the open end. L45 has a round internal shape with key slots rather than the Acmeda S45 spline profile. That internal geometry is the feature to match before ordering a motor.

L45 vs S45: why the difference matters

Both names contain '45', and from across the room they can look almost identical. But the motor does not connect to the outside of the tube. It depends on the crown and drive engaging with the inside. An S45 adaptor is therefore not a substitute for a confirmed L45 adaptor.

Can an L45 roller blind be motorised?

Yes. When the profile is confirmed, L45 can be retrofitted without replacing the tube by removing the chain mechanism and installing a compatible motor with the correct L45 crown and drive configuration.

The current L45 compatible motors page lists the motors already confirmed for this tube. At present, the L45 retrofit options are rechargeable rather than 240V hardwired motors.

Why rechargeable motors suit this retrofit

A rechargeable motor lets the blind be upgraded without bringing mains power to the window. That makes it particularly attractive when the existing blind is otherwise working well and the goal is simply to remove the chain and add motor control.

What if your tube measures 45mm but does not match L45?

Do not force the identification. It may be an S45 variant or another profile entirely. Take a clear photo of the open tube end and use our roller blind tube identifier to compare the shapes. If it still does not match, send the tube photo and outside diameter for confirmation before buying parts.

The lesson from L45 is simple: diameter gets you into the right neighbourhood; the internal profile tells you which motor adaptors actually belong in the blind.