Your search for "QSFP28" revealed the following:

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

Nvidia Mellanox MSN2100-BB2RC 16x 40GB QSFP28 F-B Air (C2P) Cumulus Linux Switch

SKU: NSB-6770
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days

Ruckus ICX7850-32Q-E2 ICX 7850 Series 32x 100GB QSFP28 Switch

SKU: NSB-6342
Condition: Seller refurbished
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 Cisco N9K-C93240YC-FX2 48x 25GB SFP 12x 100GB QSFP28 B-F Airflow Switch

SKU: NSN-1801
Condition: New
Shipping: Overnight Options
Warranty: 365 days

Extreme VSP7400-48Y-8C 48x 25GB SFP28 8x 100GB QSFP28 No Fans No PSU Switch

SKU: NSH-8529
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 Cisco N3K-C3132C-Z 32x 100GB QSFP28 Back-to-Front Airflow Switch

SKU: NSN-7552
Condition: New
Shipping: Overnight Options
Warranty: 365 days

Cisco C9500-32C-E Catalyst 9500 32x 100GB QSFP28 Front-to-Back Airflow Switch

SKU: NSH-8328
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days

NEW Cisco N9K-C92160YC-X 48x 25GB SFP28 6x 40GB QSFP+ Back-to-Front Air Switch

SKU: NSN-3866
Condition: New
Shipping: Overnight Options
Warranty: 365 days