PHP - Process Form Submission with 2 Arrays

Question

I have a web form that allows users to enter details for creating a shipping consignment for 1 more more items. They enter the address from/to fields and then there's a section where they can enter 1 or more rows for items to be included on the shipment.

When the user submits the form I get the following Array:

(
[action] => createConsignment
[type] => Outgoing Domestic Shipment
[parcelID] => Array
    (
        [0] => DS851234
        [1] => SM897452
    )



[productID] => Array
    (
        [0] => XT71121
        [1] => PL12134
    )
[ref] => 3902381720
)

which I then process to create records in a backend database like this:

foreach($_POST["productID"] as $productID) {
    
    $request->setField('productID', $productID);
}

This is working well but I now need to also include the parcelID when creating the new row in the backend database. So as well as getting the productID I need to get the parcelID with the same array position, so in the above example I would create a new row in the database with these pairs of values:

DS851234 and XT71121
SM897452 and PL12134

I can't work out how to reference both of these in the same foreach loop to get the values for the same array position at the same time.