One of the Best Ever Auto Lockout Wedge Solutions - AO63 Clear Wedge System
One of the better automotive wedge systems on the market, this one is by ProLok and it is particularly useful on cars and trucks with very stiff door sills. The metal wedge is smooth and machined so as to slide easily into the narrowest of openings, and the two plastic wedges can be used at each outer edge of the metal wedge to further open the crevice. You can also use an air wedge, such as the CDW-10A, to give even more space.
It is wise to use a good fiberoptic scope, or at least a probe light, along with this tool. "Durable" is an understatement when describing this set of tools. They will probably outlast most of your other lockout tools.