I have the Viper and the Promaster ELX ED. Believe me when I tell you that the Promaster/Hawke glass is superior to the Viper. What the Viper has is a smaller size, different feel, a faster focus rate, and a somewhat better depth of focus. Other than that the Promaster is noticeably better in resolution and anything else. I am going to have a hard time justifying keeping the Viper. Having said that, the Viper is a very good binocular, just not quite up to the other.