It is good, under the right circumstances.
This stuff works wonders. Follow the instuctions, take your time and prepare in advance. Try to get loose glass out before applying. Clean the glass to get the best adhesion from the syringe and pick a sunny day.
Now the drawback...
Most insurers will pay to have this done (apparently). If you attempt this yourself, you run the risk of leaving bubbles in the chip, which essentially means the weakness is still there. If this happens, a window care specialist cannot go over your work, as it has effectively sealed the only entrance to the crack- and you're stuffed.
I was unlucky. Whilst setting the syringe, I was working on a car stereo. I turned on the ignition, didn't realise that the stereo was resting on the screen wash stalk and the wiper blade knocked the syringe off, leaving a bubble in the chip. (This is the 4th window I've treated) so it can go wrong...
If you have the option, get it done professionally. If not, this is cheaper than a ticket from the police, a cracked windscreen and an mot failure.
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