Rheumatoid arthritis runs in my family. It causes severe inflammation and stiffness in the joints and grows progressively worse over time. My hands started locking up when I was 18.

I've written several 3DS reviews that ultimately say how uncomfortable games are to play. The actual 3D part of the handheld doesn't bother me nearly as much as the prolonged cramping my hands go through when I play for more than 20 minutes.

Handhelds just aren't comfortable. Someone, somewhere, decided that all consumer electronics just had to be paper-thin and stiff as a board and manufacturers ran wild with that concept. Add arthritis to the mix and my hands start rebelling.

The Circle Pad Pro offers some much-needed ergonomic design to Nintendo's least comfortable handheld yet. I've spent the last 24 hours playing around with it and I'm convinced it's the best $20 I've spent on a seemingly useless piece of plastic in ages. Here's why.

The shape

The Circle Pad makes it possible to hold onto the 3DS for extended periods of time. I've always had a problem with my hands hurting after playing games for too long, but with the 3DS that pain was nearly instantaneous.

The pad's slightly curved bottom fits comfortably into the hand without feeling too sculpted or bulky. The added triggers also ease a lot of the intense face button action that forced me to grip the 3DS in unnatural ways.

The weight

A 3DS I can hold onto comfortably is fine and dandy unless the added weight becomes an issue. The Circle Pad doesn't actually add much weight at all, despite having two triggers, a bumper button and an analog nub built into it.

The functionality

Right now, only Resident Evil Revelations works with the add-on, but it's a perfect game for it. Handheld shooters are usually limited to one analog stick. To aim and shoot at anything, you had to use the same stick that also moves the character around.

This isn't such a big deal, as traditionally in RE games you can't move and shoot. Well, throw on the Circle Pad and that concept is completely gone. You can move, target, and fire all without having to switch stances or lower your weapon at any time. Moving while aiming isn't exactly snappy, but you can conceivably move out of harm's way while trying to line up a shot.

Of all the things the RE series changed over the years, I'm glad to see that the stagnant stop and shoot mechanic is on its way out.

If Nintendo decides to scrap their current 3DS design in favor of a unit that has two analog nubs built into it, I doubt I'd buy it. The biggest selling factor the Circle Pad Pro has for me is the additional ergonomic grips on the bottom. I'm no stranger to bolting ridiculous accessories onto handhelds when I cannot play them properly.

Even if you aren't at risk of developing arthritis, the Circle Pad Pro offers some much-needed functionality to the 3DS and finally got the Resident Evil series to drop its horrible habit of forcing players to stand still while they shoot. I can see this accessory providing relief for left-handed gamers and for others like me who simply need something more comfortable to hold.

I'll probably still have the circle pad on my 3DS when I'm playing games that don't support it. It really isn't intrusive, and unlike all the gimmicky accessories Nintendo handhelds tend to get, this one serves a wonderful purpose.