Strapless Bra Cups (L915) use style 20 wires of the same size (i.e if you buy size W32, use W32 wires)

The cups are cross graded (sister sized), so check out the chart below to understand which of 'Our Size' you need to buy.

BRA WIRE CHART

You need to look closely, but on the inside of the cups at the bottom edge and to the outside, there are little indicator lines.  These should go to the bottom of your bra and to the arm side.  The amount of lines also indicate the size, so size 2 has 2 marks, size 3 has 3 marks etc.  the numerical size is the last digit of the SKU code, so checkout your invoice if you buy multiple sizes and forget which one is which!