People like to ask this question because Cobra Impulse System uses ATR(10) to calculate the stop loss. Actually for how to set the stop loss, I’ve already explained in details in Cobra Impulse System page. It’s in the last part of the page. For your conveniences I’ve copied the part below:

The most recent ATR value in percentage value can be found in the day’s trading signals. Say, in the signals table, I give 2*ATR(10) value in percentage, for example, today’s value, SSO = 11%, so say, tomorrow you bought SSO at 40.30, so the stop loss would be, assume you use 2*ATR(10), 40.30 – 40.30 * 11% = 35.87. If you want to use, say 1.7*ATR(10), since the table says 2*ATR(10) is 11%, so 11% / 2 * 1.7 = 9.35% = 10%, you can use 10% as your stop loss. If you find hard to understand how I get 1.7*ATR(10), you can just use the value I give in the table which is 2*ATR(10), right now at 11%. Each day the value maybe different, you just use that day’s value,  no more changes needed thereafter.