Duo supports authentication using one-time password (OTP) hardware tokens such as Deepnet SafeID. There are 2 types of OTP tokens, event-based (HOTP) and time-based (TOTP), adn Duo can support both event-based and timed based tokens. However, Duo does not support TOTP token drift or TOTP resync. As a result, TOTP tokens may eventually fall out of sync and generate invalid passcodes. Therefore, in long run, event-based token works better with Duo.
Deepnet SafeID provides both event-based and time-based tokens. Below is the list of SafeID tokens:
http://www.deepnetsecurity.com/authenticators/one-time-password/safeid/