All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
This form of investment is lawful as long as the demanded commodity which you buy becomes fully your own before you sell it. Allaah The Almighty Says (what means): {And Allaah Has permitted trade.} [Quran 2:275]
Allaah Knows best.