By weight, and the weights are nothing like equal. Most readers arrive with these five tangled together and with the two weakest ones in charge, so the whole job of this page is to put them in order. One: short commutes choose the format, because they hold the hours. Count occupied cabin hours in a normal month, split short against long. Unless your life is unusual the short column is several times the long one, and a format bought for the larger column is in daily service while one bought for the smaller column waits. The scent follows the same logic: choose something you can meet on an ordinary Tuesday rather than something that seemed impressive on a motorway. The canonical version of this argument is here and the two-hours-daily version here. Two: long trips set the level, and they set it downward. This is where readers expect to be told they need more, and it is the opposite. Two things run at once in a closed cabin. Released material accumulates, because the air exchanges slowly and hour one is still substantially present at hour four. And the nose nearest the source - whoever is driving - adapts and reports less. That mechanism owns its own page, and it means the level climbs in effect while the only person able to reduce it experiences it as fading. The timing page turns that into a procedure: nothing at the kerb, about half a commute dose an hour in. Three: passenger count decides who judges, not how much is needed. Five people in a cabin do not constitute a shortage of fragrance; they constitute five opinions, four of which are better informed than yours. The rule, and it is the most useful sentence in this family, is that the level is set for the most sensitive regular passenger, judged from the back row, in the first minute after they have got in from outside - because their accuracy expires within about ten minutes and the driver never had any. Four: food stops are not a fragrance problem. If meals happen in your vehicle, what is in the air is a source rather than a smell to be covered. Fragrance does not remove a food smell - it is material added to the same air and takes nothing away, so output over a source gives you a mixture. Wrappers out at the stop rather than at the destination, crumbs cleared from the rearmost footwells, then the fragrance question. The diagnose-first page comes before every purchase on this list. Five: changing ventilation is the only lever that acts on what is already there. Reducing a source changes what will be released from now on and does nothing about the cabin you are currently sitting in. Only exchanging the air does - fresh air rather than recirculation, windows down at intervals, doors properly open at a stop. It is also why you must never judge in the first half-minute of a reopened heat-soaked cabin. Taken in that order, here is what it comes to. Buy one 12ml unit chosen for your commute, in the form of release your temperament supports - both cost the same on every scent, so this is not a money decision. Then three free habits on the long journeys: start late, release about half, let the back row set it. Clean at the stop. Ventilate rather than add. And two things could reverse all of it. If your long trips genuinely outweigh your commuting in hours, the first variable inverts and you buy for them instead. And if you will not be the person deciding out there - somebody else drives, or the level must be fixed before anybody gets in - then restraint is not a tool you possess, and control that persists without an operator becomes worth ₹3,999: three speed settings and an auto shut-off timer at one, two or three hours. The resolving page works that through, and no page here sizes Safar to a vehicle because SOSA publishes no coverage figure for it at all.