The Nokia 5048 - NIY4437 SFP (OEM Part Number FTLF1319P1BTL-NK) is stated on Checkpoints website as a 1000Base-SX SFP, this implies that its a Multimode SFP operating at a 850nm wavelength.
However this is misleading, (or outright wrong) the SPF operates at 1310nm and is compatable with other LH GBICs like the Cisco SFP-GE-L or GLC-LH-SM.
For further info see GBIC Module and SFP Module Cabling and Connection Equipment
So its a Single-Mode SFP (SMF) rather than a Multi-Mode SFP.
