I use both everyday.
You can buy them on Amazon USA.
Nippon Kodo Viva sandalwood long box $17.30 (White box/9 in)
Nippon Kodo Mainichi koh sandalwood $9.50 (Yellow box/6 in)
Basically, you can use any incense or scent but be careful of its length.
White box is only for ancestor worship.(Ancestor care/relief/rescue)
Ancestor ritual reduces you and your family's spiritual handicap, fetters or ego.
Yellow box is multi use.
For ancestor ritual and Floor/land ritual for ghost/haunting/dead animal.
Floor care reduces your house's handicap or disadvantage, and it prevents spiritual possession.
In ancestor ritual, do not use shorter incense than "about" 5 inch.
Also, you can use broken, chipped or very short incenses "only" in floor ritual.
Although there are smoke less incense, but do not buy these for spiritual ritual.
Smoke of incense, actually the amount of particles make poor existences breathe and warm.
Plus, there is one more daily ritual without incense. It is Kamidana for nature gods who are protecting the area.
Nature worship was world wide common thing in ancient times.
Kamidana and Butsudan are two main rituals in each Japanese household.
Nature worship(Kamidana) includes ancestor worship(Butsudan) from the beginning.
Japanese core culture and spiritual barrier system, Kamidana and Butsudan were almost disappearing.
An anonymous man, IseHakusandoh, the master of Zen and Shinto revived and developed the secret white magic.