Your search for "qsfp-40g-sr4" revealed the following:
Brocade 40G-QSFP-SR4 40GB BASE-SR4 850nm MMF DDM QSFP+ Transceiver
SKU: NSH-7179
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
$ 69.99
• Only 2 remaining
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Dell QSFP-40G-SM4 77KC3 40GB BASE-SR4 850nm MMF QSFP+ Transceiver
SKU: NSB-5946
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
$ 64.99
• Only 2 remaining
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NEW Juniper 740-032986 QFX-QSFP-40G-SR4 OM3 850nm MMF 100m QSFP+ Transceiver
SKU: NSN-0947
Condition: New
Shipping: Overnight Options
Warranty: 365 days
$ 39.99
• Only 1 remaining
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Juniper 740-032986 QFX-QSFP-40G-SR4 OM3 850nm MMF 100m QSFP+ Transceiver
SKU: NSB-2055
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
$ 19.99
• 99 in stock
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NEW Dell QSFP-40G-SM4 77KC3 40GB BASE-SR4 850nm MMF QSFP+ Transceiver
SKU: NSN-0837
Condition: New
Shipping: Overnight Options
Warranty: 365 days
$ 68.99
• Only 2 remaining
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Juniper QSFPP-40GBASE-SR4 40GB BASE-SR4 850nm MMF LC QSFP+ Transceiver
SKU: NSH-5658
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
$ 33.99
• Only 2 remaining
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NEW Cisco FET-40G 40GB BASE-SR4 850nm MMF QSFP+ Transceiver
SKU: NSN-7739
Condition: New
Shipping: Overnight Options
Warranty: 365 days
$ 31.99
• Only 2 remaining
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Arista QSFP-40G-XSR4 40GB BASE-XSR4 850nm Short Reach MMF QSFP+ Transceiver
SKU: NSB-5333
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
$ 23.99
• 6 in stock
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NEW Arista QSFP-40G-XSR4 40GB BASE-XSR4 850nm Short Reach MMF QSFP+ Transceiver
SKU: NSN-3845
Condition: New
Shipping: Overnight Options
Warranty: 365 days
$ 76.99
• Only 2 remaining
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Cisco FET-40G 40GB BASE-SR4 850nm MMF QSFP+ Transceiver
SKU: NSH-5416
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
$ 21.99
• Only 2 remaining
Call if you need more