PLEASE  READ.  So  often  people  comment  without  reading  ☺️  Comment  “stretcher”  if  you  are  interested  in  having  me  DM  a  link!
This  is  actually  one  of  my  favorite  tools  (available  from  @pepetools_usa)  because  it  has  saved  me  so  much  time,  however  this  doesn’t  work  on  every  ring.  An  eternity  band  for  example  or  certain  rings  depending  on  design  would  not  be  safe  because  the  pressure  could  cause  damage.  
For  solid  rings  it  can  be  used  not  only  to  stretch,  but  you  can  reduce  (again  depending  on  shape  of  ring)  you  can  also  shape  a  wonky  ring  with  just  a  tiny  pull  of  the  lever  and  work  harden  a  bit.
This  tool  is  an  investment!  It  is  not  for  everyone  but  if  you  have  a  jewelry  business  and  you  are  producing  a  lot  of  rings  it  is  a  great  tool.
Had  you  ever  seen  this  tool  before?