Your search for "QSFP28-100G-LR4" revealed the following:

Dell QSFP28-100G-LR4 GMFC5 100GB BASE-LR4 1310nm SMF LC QSFP28 Transceiver

SKU: NSH-6164
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days

NEW Arista QSFP-100G-LR4 100GB BASE-LR4 1310nm SMF LC QSFP28 Transceiver

SKU: NSN-5317
Condition: New
Shipping: Overnight Options
Warranty: 365 days

NEW Juniper JNP-QSFP-100G-LR4 100GB BASE-LR4 1310nm SMF QSFP28 Transceiver

SKU: NSN-2071
Condition: New
Shipping: Overnight Options
Warranty: 365 days

Extreme 100G-LR4-QSFP10KM 100GB SMF 10km LC QSFP28 Transceiver

SKU: NSB-1868
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days

NEW Juniper QSFP-100GBASE-SR4 100GB BASE-SR4 850nm MMF QSFP28 Transceiver

SKU: NSN-4077
Condition: New
Shipping: Overnight Options
Warranty: 365 days

HPE Aruba JL310A 100GB BASE-LR4 LC Long Reach SMF QSFP-100G Transceiver

SKU: NSB-5547
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days

NEW Arista QSFP-100G-ERL4 100GBASE-ERL4 30-40km SMF Transceiver QSFP28

SKU: NSN-5288
Condition: New
Shipping: Overnight Options
Warranty: 365 days

Finisar FTLC1151RDPL2 100GB BASE-LR4 1310nm QSFP28 Transceiver

SKU: NSB-1160
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days

Nvidia Mellanox MMA1L10-CR 100GB BASE-LR4 1310nm SMF LC QSFP28 Transceiver

SKU: NSB-3079
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days

Arista QSFP-100G-DR 100GB BASE-DR 500m SMF QSFP28 Transceiver

SKU: NSB-5286
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days