Just place your detector rails on top of a colored block (wool, concrete, concrete powder, terracotta, glazed terracotta) and it will not activate when players are passing by without them holding that exact item in their main hand.
Just place your detector rails on top of a colored block (wool, concrete, concrete powder, terracotta, glazed terracotta) and it will not activate when players are passing by without them holding that exact item in their main hand.