288 piston uses a 13mm wrist pin where the stock 660 piston has a 12.
288/395/3120/084/088/880 wrist pin bearings are all same size and fit.
Advantages:
288 piston is the same physical height as a 660 piston but sits 1mm (0.040"") lower when fitted to the crank. I use them on a cylinder with excessive exhaust duration that I want to reduce without gaining intake duration.
There are a few tricks to fitting it in, and once its done you can't go back to a 660 piston with that cylinder.
288 pistons also have wider skirts than 660, a single 1.5mm ring with rear centre pin and a couple other little advantages when it comes to porting.
Its not something I do often, depends on the cylinder and what its going to be used for.