root@re0# set interfaces et-0/0/48 speed ?
Possible completions:
  100g                 
  10g                  
  200g                 
  25g                  
  400g                 
  40g                  
  50g                  
[edit]
root@re0# set interfaces et-0/0/48 speed  100g 

[edit]
root@re0# commit