Identifying Seitz Windows & Replacement Parts

Seitz caravan windows are now part of the Dometic range and are fitted to many Australian and imported caravans. The important step is not just measuring the opening; it is identifying the exact window family and size code before ordering blades, stays, blinds, flyscreens or seals.

Put the tape measure away at first. The safest identification method is to read the numbers moulded or printed into the window blade, usually near the top right corner when viewed from outside.

1. Confirm It Is A Seitz Window

The most common mistake is assuming a similar-looking window is a Seitz/Dometic window. Maygood, Mobicool, Cheng Bang and other copy-style windows can look close, but parts are not always interchangeable.

Check the window blade first. It may say Seitz, Dometic, Mobicool or another brand near the top corner. Then check the internal blind/flyscreen assembly and the clips that join the blind to the flyscreen. Seitz S4 clips are usually light grey, while Mobicool-style clips are different and may be clearly branded.

If your window is Maygood or Mobicool, use our Maygood / Mobicool window guide instead of ordering Seitz parts by size alone.

2. Identify S4, S4 Dlux Or S7P

The S4, S4 Dlux and S7P ranges use different parts, so identify the family before choosing a blade, stay or blind assembly.

Older S4 windows have a raised-profile acrylic blade and squared edges. S4 Dlux windows replaced many S4 options from 2019 and use a flatter acrylic panel, with the current range focused on black frame options. S7P windows have a different rounded style and different spare parts.

3. Read The Blade Size Code

The blade code normally gives the window family and size. This is more reliable than measuring the visible acrylic by eye.

For an S4 blade, a code such as AGS50700X0300 means the window size is 700 x 300. Remove the AGS5 prefix and read the remaining size.

For an S4 Dlux blade, the prefix may be MD1 or MDL. A code such as MDL0900X0450 means the window size is 900 x 450.

For an S7P blade, a code such as AGP70500X0400040 means the window size is 500 x 400. Remove the AGP7 prefix and the final suffix to read the size.

4. Measure The Frame If The Blade Is Missing

If the blade has been lost, broken off or removed, measure the outside frame rather than guessing from the hole in the wall. Then work backwards to the nominal window size.

For S4 windows, the outer frame is normally about 45mm wider and 30mm higher than the window size. For example, a 700 x 300 S4 window has an outside frame around 745 x 330.

For S7P windows, the outer frame is normally about 28mm larger than the window size in each direction. For example, a 500 x 400 S7P window has an outside frame around 528 x 428.

For a complete replacement window, also consider the wall cut-out, wall thickness, corner radius and whether the original frame has been sealed or modified. Do not order only from a rough outside measurement if the window family is uncertain.

5. Choose The Correct Replacement Blade

Replacement blades need the window family and nominal size. A 900 x 900 S4 blade, for example, should be matched from the S4/S4 Dlux family and size code rather than just from the visible acrylic panel.

Replacing a blade is usually a careful two-person job because the blade is large, flexible and easy to damage if twisted. Support the blade evenly, avoid forcing the hinge area, and compare the old and new blade before fitting.

If a blade has dropped out, inspect the hinge channel, stays and catches before simply pushing it back in. If the hinge or frame has been damaged, refitting the blade without fixing the cause may let it fall again.

6. Match Blinds, Flyscreens And Stays

For S4, S4 Dlux and S7P stays, the stay length normally follows the window height. If your window is 700 x 300, you would normally look for the 300mm stay in the matching window family.

For blinds, flyscreens and combination assemblies, use the full window size and family. Some blind/flyscreen parts are sold as assemblies rather than loose blind cloth or flyscreen mesh, so check the product listing before assuming the fabric alone is available.

If the blind and flyscreen no longer click together after dusty travel, clean the tracks and check the side runners, clips and tension before replacing the whole assembly. Red dust and debris can make the mechanism feel faulty even when the main parts are still serviceable.

7. Common Repair Traps

• Leaks at the top: water may be entering behind the outer frame, through a failed seal, or from poor fitment. Resealing usually means removing and re-bedding the frame, not just sealing the inside blind frame.
• Stress cracks: acrylic blades can crack from impact, heat, age, twisting or being over-stressed while opening. A cracked blade normally needs replacement.
• Opening too far: do not modify stays or catches just to make a blade open further. The blade can become a head-height hazard or over-stress the hinge.
• Old wind-out windows: Seitz blind assemblies are not a simple curtain replacement for unrelated old wind-out windows.
• Rubber seals: match by window family and part listing. If the seal is not shown separately, the correct repair may be a frame, blade or assembly part rather than loose rubber.

8. Shop The Correct Parts

Once you know the brand, family and size, use the matching parts category below. If the numbers or family are unclear, confirm them before ordering.