Melnais un baltais ir identiski vienādi - nevajag pirkt divus. nevienam no tiem, ne melnajan, ne baltajam nav pretvārsts un šķidrums ieplūst gāzes vadā. ;) Black and white are identical - no need to buy two. none of them, neither black nor white, has a non-return valve and the liquid enters the gas line.
Good Quality, thank you!