Un Mas Dos is the second EP by Americanindie rock band Straylight Run, released on September 16, 2008. The EP is the band's first release since they were dropped by Universal Republic and since the departure of vocalist, guitarist and pianist Michelle DaRosa. Straylight Run entered the studio on June 10 and was expected to finish work on the EP in around early August, 2008.
AbsolutePunk reviewer Adrian Villagomez awarded the album a rating of 75%. Commenting on the three songs, he noted opener "Wait and Watch" as the "angriest song on the EP, but it’s also the weakest", "Ten Ton Shoes" "is the anchor of Un Mas Dos, and the band sticks to the message already familiar to the listener – the world will beat you down and eat you alive", whilst labelling "Try" as the standout track "it deserves repeat listens... it’s tough to resist singing along to his (vocalist John Nolan's) earnest and frustrated voice as the hook grabs hold." Villagomez stated, "Switching between this EP and the band's previous material, I'm inclined to blame the production for keeping Nolan's voice too far from the forefront – this is my chief criticism with the release."