Kitchen, lavatory and specialty faucets — single-hole, centerset, widespread, pull-out, deck-mount tub, pot fillers and beverage faucets.
The three lavatory configurations are not interchangeable, and the sink decides which one you can use. Centerset fits 4" on-center holes and arrives as one unit. Widespread fits 8" to 16" and comes as three pieces, so the spout and handles are plumbed separately. Single-hole needs one hole and is the only option on most vessel and undermount installations. Count the holes in the deck before ordering, not after.
Finish is the other decision that cannot be undone cheaply. Chrome and polished nickel show water spots; brushed nickel and matte black hide them but show wear at the handle. Living finishes are meant to change over time and will not match a replacement piece bought two years later, so buy the whole suite at once if the look matters.
Check the flow rate against local code. Lavatory faucets are commonly restricted to 1.2 GPM and kitchen faucets to 1.8 GPM in states with their own standards; an aerator swap fixes an over-rated faucet, but only if the body is otherwise compliant.
