In the words of Recovery Effects:

Dirty Murals delivers complex delay and reverb with powerful controls for each, in a small 125B enclosure. Two distinct delay and reverb styles create a variety of rich, lush, ambient, textured sounds.

The first mode offers a modulated oil can style delay with shorter, vintage style repeats, paired with a small room reverb. The second mode delivers long, high fidelity, analog-style delay with a large hall reverb. The reverb level can be dialed to taste or completely removed in either mode, allowing it to function as a traditional delay pedal. The reverb can be boosted while keeping the mix low, generating the effect of a reverb with an adjustable pre-delay.