Your search for "qsfp28" revealed the following:
NEW Dell S4148T-ON 48x 10GB Copper 2x 40GB QSFP+ 4x QSFP28 F-B No OS10 Switch
SKU: NSN-9964
Condition: New
Shipping: Overnight Options
Warranty: 365 days
Nvidia Mellanox MSN2100-CB2FO 16x 100GB QSFP28 B-F Air (P2C) ONIE Switch
SKU: NSB-6766
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
NEW Extreme SLX9250-32C SLX 9250 Series 32x 100 Gigabit Ethernet QSFP28 Switch
SKU: NSN-3734
Condition: New
Shipping: Overnight Options
Warranty: 365 days
NEW Dell S4148T-ON-RA 48x 10GB Copper 2x 40GB QSFP+ 4x QSFP28 B-F OS10 Switch
SKU: NSN-8125
Condition: New
Shipping: Overnight Options
Warranty: 365 days
NEW Dell S4148FE-ON-RA 48x 10GB SFP+ 2x 40GB QSFP+ 4x QSFP28 B-F No OS10 Switch
SKU: NSN-9967
Condition: New
Shipping: Overnight Options
Warranty: 365 days
NEW Nvidia Mellanox MSN2700-CS2FC 32x 100GB QSFP28 B-F Air Cumulus Linux Switch
SKU: NSN-0210
Condition: New
Shipping: Overnight Options
Warranty: 365 days
NEW Cisco N9K-C93108TC-FX3P 48x MultiGB UPoE RJ-45 6x 100GB QSFP28 BF Air Switch
SKU: NSN-0629
Condition: New
Shipping: Overnight Options
Warranty: 365 days
NEW Nvidia Mellanox MSN3700-CS2F 32x 100GB QSFP28 B-F Airflow (P2C) Onyx Switch
SKU: NSN-0691
Condition: New
Shipping: Overnight Options
Warranty: 365 days
NEW Extreme EN-SLX-9030-48S-4C 48x 10G SFP+ 4x 100G QSFP28 No Fans No PSU Switch
SKU: NSN-5026
Condition: New
Shipping: Overnight Options
Warranty: 365 days
Cisco Meraki MA-CBL-100G-3M 3m 100GB QSFP28 Stacking Cable for MS450 MS355
SKU: NSB-6434
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days