This product is a great solution to when you're not sure which tip to buy.  The kit comes with 7 PS-90 tips so you can evaluate them then buy packs of 5 for the ones you really need.

Kit includes one of the following:

1121-0414

1121-0337

1121-0360

1121-0361

1121-0510

1121-0358

1121-0527

1121-0526