A 50/50 means riding straight across a box with the board parallel to the feature. Approach straight, ride up the ramp, and keep your base flat on the surface. The box is slippery. Don't try to edge on it.
The secret to boxes is that they're essentially frictionless compared to snow, so anything you try to do on them (edge, push, steer) happens way more aggressively than you expect. That's why "flat base, quiet body" is the whole technique. Stand over the board like a statue and let it carry you across. Your feet should feel equally weighted on both edges with no pressure on either one.
Pick a flat, low box for your first few tries. Look for the kind that's barely raised off the snow. Approach the onramp straight-on, matching the speed you'd use on a gentle groomer. Ollie onto the box (a small pop is enough) and land with the box centered between your bindings. Look at the far end of the box as you slide, not at your feet. Ride off the end with the board still flat, wait a second, then turn once you're back on snow.
Watch more here:
Source: Johnathan Buckhouse · How To 50:50 A Box or Rail On A Snowboard!!
Key tips
- Approach straight, not at an angle
- Keep your base flat. Edging on a box will catch and throw you
- Weight centered, knees slightly bent
- Look at the end of the box, not down at your feet
- Ride all the way off the end before turning