Review on Dylos DC1100: The Ultimate Laser Particle Counter for Accurate Air Quality Analysis by Daryl Fitch

Seller has a 30 day return policy. The manufacturer offers a 90-day warranty against "defects in materials or workmanship". Well, one thing can be said for them, they know their build quality. It worked reasonably well until a week after the 90-day warranty expired. The reading started jumping around +/- 4000 fine particles for about a minute and now only reads 0/0. He was treated gently. $300 is a TON for this device, even if it has worked reliably. This is certainly an exaggeration for a product that only lasted 3 months with occasional use. And why a serial interface instead of USB? What is that, 1987? Registration via the serial port is only updated once per minute. So annoying. Overall, it looks like this product was designed by an amateur as "the first real product". It'll cost you about 20% of what this one costs, and at least you can use it to replace the $10 part if/if it breaks.