This Rant sprocket is a great value alloy replacement that bikes that come with heavy, easily-bent stamped steel sprockets (most bikes sub-400) and it comes in 25 or 28T.

25Tor 28T
6061-T6 alloy.
15/16 bore (24mm compatible). So fits a three piece crank with a 24mm spindle and also One Piece cranks.
Includes 19mm & 22mm adaptor
Weight:70gfor 25T