Pretty much what the summary says, these are the 1x1x6 Gridfinity storage bins, with 5mm of width removed to make them only 37mm wide. This allows the addition of another 5 (slightly smaller) bins to the smaller Durham hardware storage trays/drawers, for a total of 40 bins. These drawers are not cheap, and the additional 5 bins will help you get the most out of your storage investment.
They're unfortunately just a little too narrow for the larger Durham drawers, but I didn't want to make them any smaller. I may or may not narrow them further for those drawers, but I'm not planning to at this time since the 10x7 grid that will fit in the larger ones wastes less space in relative terms. Also, I have fat fingers so there's a limit to how small I can make them and still have them be useful to me.
Like my other Gridfinity models, these are modified to accept 6x3 magnets as a press fit, with the upper surface of the magnet holes modified to make the slicer bridge across correctly for a clean result.
Amazon link to the Durham trays these are designed for:
The author remixed this model.