$sizes-em: (
  'x-50' : 0.50,
  'x-75' : 0.75,
  // 1em
  '1x' : 1,
  '1x-25': 1.25,
  '1x-50': 1.50,
  '1x-75': 1.75,
  // 2em
  '2x' : 2,
  '2x-25': 2.25,
  '2x-50': 2.50,
  '2x-75': 1.75,
  // xem
  '3x' : 3,
  '4x' : 4,
);

@each $prop,
$abbrev in (width: w, height: h) {

  @each $size,
  $length in $sizes-em {
    .#{$abbrev}-#{$size} {
      #{$prop}: #{$length}em !important;
    }
  }
}