MaXalami tubeless tyre repair kit allows you to repair your MTB, CX or Road tubeless tyres from the outside permanently. You simply thread the appropriate worm into the applicator tool and insert into your tyre. Be sure to get the worm in fully (get the widest part of the applicator past the tyre casing and it helps if you angle it as you don't want to damage your rim tape). Then place your thumb over the inserted worm and withdraw the tool. Alot of worm will stick out of the tyre but that will flatten off as you ride and fall away.
The large refers to the size of the worms. These are whoppers 3.5mm wide and 10cm long.
Maxalami is a German company. Obviously German punctures are bigger hence these worms. I have even plugged the tyre on a Royal Mail van with one of these so that my mail got to the sorting office. In a car tyre though they are not permanent but it is better than walking.