These files are served from memory and generated on the fly.
1MB.bin, 10MB.bin, 100MB.bin, 1GB.bin, 10GB.bin, 100GB.bin, 1TB.bin, 1PB.bin, 1EB.bin
Download from command line:
wget -4 -O /dev/null https://speedtest.nexalus.net/10GB.bin # IPv4
wget -6 -O /dev/null https://speedtest.nexalus.net/10GB.bin # IPv6