Your search for "QSFP28" revealed the following:
Dell S4148T-ON 48x 10GB Copper 2x 40GB QSFP+ 4x 100GB QSFP28 F-B No OS10 Switch
SKU: NSB-9788
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
NEW Dell N3248TE-ON 48x 1GB RJ45 4x 10GB SFP+ 2x QSFP28 F-B Air OS6 Switch
SKU: NSN-9969
Condition: New
Shipping: Overnight Options
Warranty: 365 days
NEW Dell S4112T-ON 12x 10GB Copper 3x 100GB QSFP28 F-B Air AC (No OS10) Switch
SKU: NSN-9954
Condition: New
Shipping: Overnight Options
Warranty: 365 days
NEW Nvidia Mellanox MCP1600-C002E30N 2m 100GB QSFP28 Direct Attach Copper Cable
SKU: NSN-8964
Condition: New
Shipping: Overnight Options
Warranty: 365 days
Ruckus ICX7850-48F-E2 48x 25GB SFP28 8x 100GB QSFP28 Switch
SKU: NSB-6341
Condition: Seller refurbished
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
Cisco N540-28Z4C-SYS-A NCS 540 28x 10GB SFP+ 4x 100GB QSFP28 Router
SKU: NSB-8202
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
Cisco N3K-C3132C-Z 32x 100GB QSFP28 Back-to-Front Airflow Switch
SKU: NSH-8346
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
Dell N3248TE-ON 48x 1GB RJ45 4x 10GB SFP+ 2x 100GB QSFP28 F-B Air OS6 Switch
SKU: NSB-8625
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
NEW Dell N3248TE-ON-RA 48x 1GB RJ45 4x 10GB SFP+ 2x QSFP28 B-F Air OS10 Switch
SKU: NSN-9971
Condition: New
Shipping: Overnight Options
Warranty: 365 days