Your search for "QSFP28" revealed the following:
NEW Cisco NCS-5002 NCS 5000 80x 10GB SFP+ 4x 100GB QSFP28 B-F Airflow Router
SKU: NSN-0675
Condition: New
Shipping: Overnight Options
Warranty: 365 days
Mellanox MSN2100-BB2FC 16x 40GB QSFP28 B-F Airflow (P2C) Cumulus Linux Switch
SKU: NSB-6769
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
Mellanox MSB7780-ES2F SB7780 36x 100GB QSFP28 EDR B-F (P2C) InfiniBand Router
SKU: NSB-6818
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
Extreme SLX9250-32C-AC-R SLX 9250 32x 100G QSFP28 B-F Air Switch
SKU: NSH-9999
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
Extreme 10401 100GB BASE-SR4 850nm MMF MPO QSFP28 Transceiver
SKU: NSB-5517
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
NEW Extreme Brocade BR-SLX-9140-48V-AC-F 48x 25GB SFP28 6x QSFP28 F-B Air Switch
SKU: NSN-3852
Condition: New
Shipping: Overnight Options
Warranty: 365 days
Extreme VSP7400-32C-AC-F VSP 7432CQ-F 32x 100G QSFP28 F-B Airflow Switch
SKU: NSH-8499
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
Nvidia Mellanox MSN2700-CS2R 32x 100GB QSFP28 Front-to-Back (C2P) Onyx Switch
SKU: NSB-6735
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
NEW Cisco N9K-C92300YC 48x 25GB SFP+ 18x 100GB QSFP28 Front-to-Back Air Switch
SKU: NSN-8177
Condition: New
Shipping: Overnight Options
Warranty: 365 days
EdgeCore AS5916-54XM-O-48V-F 48x 10GB SFP+ 6x 100GB QSFP28 F-B Air (DC) Switch
SKU: NSB-2313
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days