Common attachment styles include clip-on or snap-on strainers that secure to pots or bowls, sink strainers with rims or silicone undersides that sit in the drain, and removable stopper/strainer combos that seal the sink for filling.
Typical listed sizes range from compact handheld/sink strainers (example: about 4.3 in × 1.5 in × 4.3 in, head diameter ≈ 0.75 in), mid-size handheld strainers (about 9 in × 5 in × 3 in), to larger colanders (about 11 in wide × 9.3 in deep × 4.5 in high).
Listings show both hole-style drainage (drainage holes) and fine-mesh constructions. Some sink strainers use a silicone basket that flips inside out, and certain models combine straining with a stopper function.