Not ideal, but ....

Switch off on a small mower Wolf thirty years. Do not do to have only the cable connection to start stop the blade. And dangerous. Having found that this model (among several vendors), I ordered it.
Fixing on the rather delicate mower. We must break the grip. Difficult to break through a tube. Besides the mine lacked a little tube diameter so that it fits perfectly. But it worked. Two son to plug in and switch is in place.
To start, you must press the yellow button before tightening the grip on the handle of the mower. At the slightest relaxation of it goes back button and start again. It annoys a bit. But ç'est security.

In summary, a pricey product, difficult to position depending on the shape of the handle of the mower (the handle must have sufficient race, but not too much ...) and set.
In addition, this switch is sold according to its capacity, expressed in amperes. Would it not be simpler to offer different models depending on the power of the mower (watts)?
But it works properly and avoided me to buy an expensive mower. This 3 star.