2E PCIE slot cover for cases E185, E190-3U, E171, E1802-500

I'll get straight to the point, is there an easy way to know what PCIe slot on a mATX motherboard lines up with what slot on a case?

Description IO Port anti dust cover Protect the IO ports from dust and oxidation Fits your PC, Mac, AV equipment, Cell phone etc

pcie2 slot SilverStone Technology Upgrade your computer with SilverStone Aeroslots-BP maximum vented PCIe slot cover 4-pack in powdered black

pcie slot gpu Ventilated PCI Express Slot Cover Computer PC Slot Bezel Perforated Plate Hole B ; Quantity 20 sold 1 available ; Item Number 285166698715 ; Marke NA