This is what I got. Mellanox has approved cables/QSFP+ list of their website, I just asked re-distributor to sell me "approved" cable.
ORDER DETAILS UNIT PRICE TOTAL
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QTY 1
SKU MC2210310-005
PRODUCT Mellanox Active Fiber Cable, Ethernet, 40GbE, 40Gb/s, QSFP, 5 meters, Part ID: MC2210310-005
PRICE $316.00
Regards,
Philip