It's great to find things with clear dome lids. they really hold humidity in, which is good until the first seedlings emerge.
Be sure to punch holes in the bottom for drainage!
It seems to me that if the tray or cup has biggish holes, and sits on a water-absorbent mat like cotton cloth, the bottom layer of soil mix drains better, which gives the deeper roots better aeration when I over-water.
And I like to add fairly coarse pine bark mulch chips & fibers (screened to around 1/8" to 3/8") for the same reason: encourage more water to drain out, so air can get to the roots. I don't like much peat or other fines in mt seed starting mix.
However, very fine seeds that need light and should be on the surface or barely covered NEED a fine surface, or they fall into crevices and never sprout. That's when I spread a little vermiculite on top of the shredded bark.
