Your search for "QSFP-40G-SR4" revealed the following:

Cisco Meraki MA-QSFP-40G-LR4 40GB BASE-LR4 1310nm SMF QSFP+ Transceiver

SKU: NSB-0838
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days

Fortinet FG-TRAN-QSFP+SR 40GB BASE-SR4 850nm LC DOM QSFP+ Transceiver

SKU: NSB-1405
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days

NEW Ruckus E40G-QSFP-SR4-INT 40GB BASE-SR4 850nm OM3 MMF QSFP+ Transceiver

SKU: NSN-1020
Condition: New
Shipping: Overnight Options
Warranty: 365 days

NEW Nvidia Mellanox MC2210411-SR4L 40GB BASE-SR4 850nm DOM MMF QSFP+ Transceiver

SKU: NSN-1684
Condition: New
Shipping: Overnight Options
Warranty: 365 days

F5 OPT-0036-01 F5-UPG-QSFP+ DOM 40GB BASE-SR4 MPO-12/UPC MMF QSFP+ Transceiver

SKU: NSB-0847
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days

NEW Arista QSFP-100G-CWDM4 100GB BASE-CWDM4 SMF Optical QSFP28 Transceiver

SKU: NSN-5677
Condition: New
Shipping: Overnight Options
Warranty: 365 days

NEW Cisco Meraki MS450-12-HW 12x 40GB QSFP+ 2x 100GB QSFP28 Unclaimed Switch

SKU: NSN-3730
Condition: New
Shipping: Overnight Options
Warranty: 365 days

NEW Cisco Meraki MS355-24X2-HW 24x mGig UPoE 4x SFP+ 2x QSFP+ Unclaimed Switch

SKU: NSN-3600
Condition: New
Shipping: Overnight Options
Warranty: 365 days

NEW Cisco Meraki MS355-24X-HW 16x 1GB 8x mGig UPoE 4x SFP+ 2x QSFP+ Unclaimed

SKU: NSN-3597
Condition: New
Shipping: Overnight Options
Warranty: 365 days