We will be closing for the festive season from 21 December 2022 and reopening on the 16 January 2023

Custom Filters

This is where you design the filter to suit your need. We can make any shape and size filters to your exact specifications. We will accurately manufacture the filter to the measurements you give us. You may also choose the color of the frame and mesh from our colour range.

You may order 1 filter if you so prefer and the cost of the filter will be in line with the rest of our filters.

Here are a few pointers to keep in mind when designing your filter.
Please follow the instructions below to guide you in your design.


Measure the size of the vent that you need filtered. These will be either the inside dimensions (I/D), or outside dimensions (O/D), depending on your case. Use the table below as a guide for the frame width to determine your I/D or O/D.
If there are obstacles on the outside, like screws or protrusions, work with the O/D, so the outside of the filter fits the opening exactly.
E.g. in the image above, the vent size is 120mm x 134mm. This will be the O/D. The filter will have an 11mm frame. Please note that the frame width has to be added twice (11mm for each side). The I/D will then be 98mm x 112mm.

Below is a guide to help you determine the appropriate frame width. The minimum frame width on any filter is 10mm. The width of the frame will increase as the size of the filter gets bigger as shown below.
The reason for this increase in width is to ensure the structural integrity of the filter, but this is only a guide.
DEMCiflex Filters have a low profile design.
< 2.5mm thick without the non-ferrous magnet and < than 3mm with the non-ferrous magnet included.

Frame lengthFrame width
151mm - 180mm12mm
180mm -200mm13mm
201mm - 300mm 14mm
above 300mm15mm

If the filter is in a recess or has a shape that is hard to measure we suggest that you cut the shape out of stiff paper or board. You can then fit this cutout into the desired position and trim it until it fits exactly the way you want. Please see images below. Write your email address, and which filter it is on the cutout, and send the cutout to the following address, or scan and email it to the address below

DEMCifilter SA

P.O. Box1127

Cape Gate



South Africa

Determine if the material where the filter should fit is ferrous or non-ferrous. Magnets will cling to ferrous materials (metals containing iron Fe) but not to non-ferrous materials (acrylics or aluminium).

You can send us an email to request a quotation for your custom filter.
Please include the following:

1. Quantity
2. Size (I/D and O/D)
3. Ferrous/ non-ferrous
4. Colour of frame
5. Black or white mesh
6. Country to which the order will be shipped (this is to include a shipping quotation)
3x O/D 500mm x 168mm (I/D 470mm x 138mm) non-ferrous black frame/black mesh

MAXIMUM SIZE IS 690mm x 510mm. If the filter you need is bigger than this, consider breaking it up into 2 or more smaller filters. This will also make it easier to clean and maintain.