Tamsulosin is an alpha blocker usually prescribed for urinary complaints that has been shown to have some benefit in allowing kidney stones to pass through the ureter. Silodosin is a new alpha blocker that acts more rapidly than tamsulosin and has been shown to have specific receptors on the ureter. The investigators would like to see if there is some benefit to taking silodosin over tamsulosin after extra-corporeal shock wave lithotripsy (ESWL) to break kidney stones in terms of allowing the ureteral fragments to pass through the ureter. Our hypothesis is that silodosin will be at least as effective as tamsulosin in terms of allowing stones to pass, but may allow them to pass more quickly because of the rapid onset of action.