For the shipment received by Leszek Kieltyka on 2017/9/25, what was its weight?
on 2017/9/25 refers to ship_date = '2017-09-25'
SELECT T1.weight FROM shipment AS T1 INNER JOIN driver AS T2 ON T1.driver_id = T2.driver_id WHERE T2.first_name = 'Leszek' AND T2.last_name = 'Kieltyka' AND T1.ship_date = '2017-09-25'