Denne er 7x21 cm

You can but the magnetic foil with a hobby knife or a good scissor

rivebestandighed 3 (Newton)

Ensure they are sewn so that they make direct contact with each other

These are 7x21 cm

Sy-i-magnet knap rund Ø26 mm., mørk lilla Auto-translated (EN) Denne er 7x21 cmColored buttons with magnets in, designed for sewing into clothing, curtains etc. with simply a needle and tread no need for a fancy sewing mashine here. Each unit contains of two parts with buttonholes. You get one north and one south every time you order 1 unit. So 1 unit gives you 1 set 10 units gives you 10 sets. Generally, 5 button units are adequate for a standard jacket or shirt (though preferences vary). This model is a dark purple color,