Your search for "QSFP28" revealed the following:
Nvidia Mellanox MSX6025T-1SFS SX6025 36x 40GB QSFP FDR10 B-F Air (P2C) Switch
SKU: NSB-2856
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
Cisco EPA-QSFP-1X100GE ASR 1000 Series 1x 100GB QSFP100 Router Port Adapter
SKU: NSH-9307
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
Juniper EX4400-48T-AFI 48x 1GB RJ-45 1x Expansion Module Slot B-F Air Switch
SKU: NSB-7904
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
Juniper EX4400-48T-AFO 48x 1GB RJ-45 1x Expansion Module Slot Switch
SKU: NSB-7902
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days