Kartboy Shifter Bushing Combo Subaru 2004-2019 STI
This is a very nice package from Kartboy that saves you a couple of bucks (which is always nice). What you're looking at is the front and rear stay combo pack for Subaru 6MT transmissions.
You should already know about the front stay bushing because it's pretty famous. In fact, this is usually the first mod anyone does to their Subaru. It's easy enough for a newbie, and the benefit is great enough for the old timers to enjoy it as well.
As for the rear stay bushing - this one hasn't been on the market as long, but it quickly gaining in popularity. Heck, as long as you're in the area doing the front bushing, why not just do the rear at the same time?
What these do: These bushings greatly enhance the feel of the stick by replacing the stock, super soft bushings with units that are made from a much stiffer urethane. The net result is a crisper and more solid feel in the forward and back motion of the stick.