This is self adhesive tear away stabiliser.
This backing can be used in the same way as iron on (but without having to use the iron) but it is more versatile than that. It can be hooped up with the backing paper upwards & the paper torn away to reveal a sticky surface. The item to be embroidered is stuck to the stabiliser.
This means that you can embroider on items smaller than the hoop like neckties, corners of handkerchiefs and napkins etc. You can also use it with fabrics with a fragile pile (like chenille etc.) which could be damaged if crushed in the hoop.
When you come to remove the item from the hoop, simply tear the embroidery towards the middle of the design. You will be left with a hole the shape of the design and if the backing is still sufficiently sticky (it usually is if you are sewing on non-fluffy fabrics like cotton but not with fleece etc.) you can patch the filmoplast with a peice stuch on (sticky side up). You end up with scraps for doing this from the bits that are clamped in the frame when you hoop it up. You can often do 3 designs on 1 hooping.
It is especially useful when sewing on stretch, knitted or unstable fabrics.
As it provides quite a light stabiliser, if you need more stabilising you can just 'float' a piece of ordinary tear away underneath the hoop
Tears away as normal.
Picture shows the filmoplast folded over to show the stabiliser on the back and the squared paper, which gets torn off, on the front.
It is 50cm wide and this is 1 metre off the roll.