Last updated: 29 July 2026
A framed shower door magnetic strip may look like a simple replacement part, but choosing the right one is often less about finding a similar shape and more about checking whether it will fit the existing track.
Supplier drawings may show measurements such as 7mm, 9mm, 10mm, 3mm and 1mm, without making it clear which ones actually affect the fit. Glass thickness alone is not enough, and comparing the front profile is not reliable either. At the same time, there is no need to measure every dimension shown on the drawing.
When choosing a T-shaped framed shower door magnetic strip, first check whether the T-head will fit the existing track and whether the track opening is suitable. Once the strip can be fitted securely, check the magnetic reach. On a sliding door, this means the maximum track-to-track distance a pair of seals can cover. On a hinged door, the magnetic reach needs to be close to the actual closing gap.
What Is a T-Shaped Framed Shower Door Magnetic Strip?
This type of magnetic shower seal fits inside the aluminium frame of a shower door. Rather than clipping directly onto the glass, it fits into a track using a T-shaped fixing section.
The T-head is the wider fixing section on the seal. It sits inside the T-slot, the T-shaped channel within the aluminium frame. The track opening is the narrower entrance to that channel.
Although many replacement strips look similar from the outside, their fixing sections can vary. Some have a wider T-head, some have a narrower neck, while others sit deeper inside the track.
This means that two magnetic strips can look almost identical from the front without being interchangeable. The section that fits inside the track is the part that matters most.
When the existing magnetic seal clips directly onto the edge of the glass rather than fitting into an aluminium frame, see our Frameless Magnetic Shower Door Seal Guide instead.
Why Glass Thickness Is Not the Main Measurement
Most frameless magnetic shower door seals clip directly onto the glass edge, so glass thickness is usually the first measurement to check, whether the glass is 6mm, 8mm or 10mm.
A T-shaped framed shower door magnetic strip works differently.
Because it fits into the aluminium frame rather than onto the glass, glass thickness is not usually the deciding measurement. Two shower doors may use the same thickness of glass but still require completely different magnetic strips when their track profiles differ.
A quick way to tell is to look at the end profile of the existing strip. When it has a horizontal T-shaped head that sits inside the frame, the replacement should be chosen by matching the track profile rather than the glass thickness.
Which Measurements Actually Matter?
Supplier drawings normally show the complete profile, so it is common to see several different dimensions.
Not every measurement affects whether the replacement will fit.
A new magnetic strip does not need to match every external dimension of the original. What matters is whether it fits securely inside the existing track and whether the magnetic closing edge reaches the correct position once installed.
When those two points are right, small differences in the outer profile, body height or magnet housing will not normally affect how the strip works.
For most replacements, only two checks matter.
Step 1: Check the T-Head and Track
Taking the product shown as an example, the T-head is around 7mm wide.
The track therefore needs enough internal space to accept a 7mm T-head. Its opening must also be narrower than the head so that the strip remains held in place once fitted.
The opening cannot be too narrow, though. The centre section measures around 3mm, with about 1mm on either side. In practice, the track opening normally needs to be slightly more than 5mm for the strip to pass through during fitting.
For this profile, the inside of the track needs to accommodate a T-head around 7mm wide, while the opening should be more than about 5mm but less than 7mm.
An opening below about 5mm is unlikely to let the strip pass through. At 7mm or wider, the T-head may not be held securely and could pull back out of the track.
To check this, remove a short section of the existing seal and look at its end profile. Start by measuring the width of the T-head, then check the track opening. There is no need to copy every dimension shown on the supplier’s drawing.
Step 2: Check the Magnetic Reach
Once you know the strip fits the track, check whether the magnetic closing edge can reach the correct position.
The measuring method depends on how the shower door closes. Sliding doors and hinged doors work differently, so they should not be measured in the same way.
Sliding Doors: Measure Between the Tracks
On a sliding shower door, the two magnetic strips normally meet face to face when the door is closed.
Measure from one T-slot fixing position to the other with the door fully closed. Do not measure only the visible gap between the two magnetic edges.
The visible gap can be misleading because part of each strip sits inside the aluminium track. Measuring from track to track shows the full distance that the pair needs to cover.
In this example, each strip extends around 9mm from its T-slot fixing position, giving the pair a combined coverage of about 18mm.
For a sliding door, 18mm is the approximate maximum track-to-track distance this pair can accommodate. The measured distance does not have to be exactly 18mm. As long as it remains within that range, the two magnetic edges should still be able to meet when the door closes.
A track-to-track distance of around 15mm, for example, may still be suitable because it falls within the pair’s approximate 18mm coverage.
Hinged Doors: Match the Closing Gap
Hinged and pivot shower doors work differently.
As the door closes, the magnetic strip normally extends from the door-frame track towards a fixed frame, wall profile or another magnetic strip. Rather than checking the distance between two tracks, compare the magnetic reach with the actual closing gap.
Measure from the T-slot fixing position to the surface where the magnetic strip needs to close.
A gap of around 15mm will normally require a strip with a similar effective reach.
When the reach is too short, the magnetic edges may not make contact. When it is too long, the strip may touch the frame or opposing seal before the door has fully closed.
For sliding doors, the main check is whether the track-to-track distance stays within the pair’s maximum coverage. For hinged and pivot doors, choose a magnetic strip with a reach close to the actual closing gap.
Why Similar-Looking Strips May Not Be Interchangeable
Once fitted, most of the fixing section is hidden inside the aluminium frame. From the outside, only the magnetic closing edge remains visible, making it difficult to tell whether two strips have the same internal profile.
Some strips have a similar T-head width but a different centre section, so they require a different track opening. Others fit the same track but extend a different distance towards the closing edge.
This does not mean that every external measurement has to match exactly. Provided the T-shaped fixing section suits the existing track and the magnetic edge reaches the correct closing position, small differences that do not affect fitting or sealing are usually acceptable.
What to Do Next
Once you have confirmed the T-head size, track opening and required magnetic reach, browse our Shower Door Magnetic Strips collection and compare the end profiles and recommended closing gaps.
Still unsure? Rather than taking more measurements, send us a clear photo of the end profile, a photo showing the key dimensions beside a ruler, and a full photo of the shower door in its closed position. Contact us by WhatsApp or email, and we will use the track profile, door type and closing gap to help identify a suitable replacement.
A matching profile may not always appear in the collection because framed shower door magnetic strips come in many different shapes, and not every model is listed online. SIMBA manufactures more than 9,000 seal profiles, so we may still be able to find a suitable option from your photos and measurements.
Related Guides
Why Magnetic Shower Door Seals Stop Working
About the Author: Laura
Laura joined SIMBA in 2017. She works with shower seal product information, customer enquiries and replacement guides for the UK market.