This is a naive model (caveat lector!). The general parameters are based on what has been broadly described in the popular meeting:
Patients are asymptomatic for about 2 weeks;
Patients are infectious for about 1 week;
Each infectious patient (potentially) transmits the disease to 2 others; and
30% of those infected recover and become immune.
The model allows each of these parameters to be changed.
Noteworthy: In this simple model every one gets infected if R>1; which is why reducing the transmission rate is so critical. Equally critical is reducing the period of time over which the transmission is possible.