The Cokin P103 Close-Up +3 Filter is the filter you need if you wish your lens to focus closer than it does. This is the simplest and least expensive method of close-up photography.
A +3 close-up lens will allow you to focus closer than the +1. The maximum magnification achieved with these attachments will depend on the focal length of your lens as well as the actual close focusing capability of that particular lens.
This filter measures 85 x 85mm and fits the Cokin P series holder.