I bought two, but when both of the batteries of the trial runs out, I could not use it even after replacing the batteries. It seems not to be a poor contact of the battery contacts. At least I want you to have 2 new batteries.
Sensitivity is very bad and there are times when the lights are turned on and off, even though they passed under exactly the same conditions. The battery included in the instruction is for the purpose of confirming the operation to the last, when it is used it was to change to a new one, so I bought batteries, but the behavior has not changed at all, I feel cheated twice. We recommend not to buy this product.