To make a true test you will need a detector with air sampling pump (sucking probed air into the sensor).
You’re looking at approx £150. Otherwise - any cheapo will do (don’t overpay).
Have a look here:
To make a true test you will need a detector with air sampling pump (sucking probed air into the sensor).
You’re looking at approx £150. Otherwise - any cheapo will do (don’t overpay).
Have a look here: