Vector of 3 integers: min, default, max.

• min - amount of memory reserved for send buffers for TCP socket. Each TCP socket has rights to use it due to fact of its birth. The default value is 4096 bytes.
• default - amount of memory allowed for send buffers for TCP socket by default. This value overrides wmem_default used by other protocols, it is usually lower than wmem_default. The default value is 16384 bytes.
• max - maximal amount of memory allowed for automatically selected send buffers for TCP socket. This value does not override wmem_max, "static" selection via SO_SNDBUF does not use this. The default value is 4194304 bytes.