No wonder they're so cheap - SIG SAUER OPMOD Romeo5 Compact 1x20mm Reflex Red Dot Sight

Today was the first time I've ever used this red dot. After zeroing the sight in, all was well. Around 120 rounds later, the red dot just disappeared and never came back on. Thought maybe it was the battery, but no. I planned on using this red dot on my home defense rifle, but if this is what to expect, I'd never get another one.