All is well, satisfied with the purchase. Thanks to the seller.
Initially I thought it is not working, because it did not give any alarms when I exposed it to gas...then I discovered that it need more gas to be triggered, it is also indicates the amount of gas it detects, but you can not adjust the sensitivity for triggering. The built in siren will not wake you up, unless you are sleeping in the kitchen, so you will need to rely on your mobile alarm or other siren.