Your search for "QSFP28" revealed the following:
NEW Mellanox MCX414A-BCAT ConnectX-4 2x 40/56GB QSFP28 PCIe3.0 x8 Card
SKU: NSN-1120
Condition: New
Shipping: Overnight Options
Warranty: 365 days
NEW Ruckus ICX7850-48F ICX 7850 Series 48x 25GB SFP28 8x 100GB QSFP28 Switch
SKU: NSN-8061
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 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 Juniper EX9251-8X4C EX9250 Series 8x 10GB SFP+ 4x 100GB QSFP28 Switch
SKU: NSN-3533
Condition: New
Shipping: Overnight Options
Warranty: 365 days
NEW Juniper EX4650-48Y-AFI 48x 25GB SFP28 8x 100GB QSFP28 B-F Air Switch
SKU: NSN-3465
Condition: New
Shipping: Overnight Options
Warranty: 365 days
NEW Arista DCS-7500RM-36CQ-LC 7500R Series 36x 100GB QSFP28 Switch Line Card
SKU: NSN-9205
Condition: New
Shipping: Overnight Options
Warranty: 365 days
NEW HPE Q2F21A SN2700M M-Series 32x 100GB QSFP28 Switch
SKU: NSN-2408
Condition: New
Shipping: Overnight Options
Warranty: 365 days
NEW Arista DCS-7280TR-48C6-R 48x 10GB Copper 6x 100GB QSFP28 B-F Airflow Switch
SKU: NSN-3567
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