передача параметров в массив

<?php
$weights = array( "100:150", "200:250", "300:350", "400:450" );

foreach ( $weights as &$weight ) {
  list( $paramprice, $param ) = explode( ":", $weight );
  $weight = '<option value="'.$paramprice.'">'.$param.'</option>';
}

unset( $weight );
echo '<select>';
foreach ( $weights as $weight ) {
  echo $weight;
};
echo '</select>';