The converter is an open-bottomed frame with a 24.8mm pocket sized to accept a 25mm square base. Push the base in from the top — it clicks into a snug friction fit. The underside opening is smaller (21.8mm), so the base physically cannot fall through — it locks in place. The top edge of the base sits flush with the top edge of the converter, giving a seamless, unified appearance. No glue, no magnets, no modification to your model.

To remove, push the base out through the underside opening from below — you never need to grip the model itself, so there's no risk of damaging paintwork or breaking fragile parts. The smaller underside opening is a deliberate retention feature.

Injection-moulded from ABS plastic — same material, same tooling quality as our base range. The textured surface matches the OBS bases so the converter and base look like a single piece. The 24.8mm inner pocket grips the 25mm base securely — a snug fit, not a loose rattle. The 21.8mm underside opening is smaller than the pocket, so the base is mechanically retained and cannot fall through.

Every converter in the OBS range is designed in-house using industry-standard CAD. The pocket dimensions are engineered specifically for OBS 25mm square bases. The outer width matches 30mm nominal exactly at the bottom edge — correct for ranked formation placement.

Designed for OBS 25mm square bases — both plain and slotted variants fit. Drop in your based model and the converter presents a 30mm square footprint for systems that have moved from 25mm to 30mm infantry sizing. No need to strip, rebase, or risk damaging painted models.

The converter works with third-party 25mm square bases too, though fit may vary slightly. Designed and tested for the tightest fit with OBS bases. The converted model sits at the correct height and footprint for tournament and competitive play.

Part of the Open Basing System (OBS)

One Ecosystem · Every Size · Every Shape

OBS is a modular basing ecosystem designed as a whole — not a random collection of bestsellers. Every size, shape, converter, and tray is planned to work together. Independent and gamer-built.

New products added regularly — the OBS range is always growing.

Push the 25mm base into the converter from above. It should click into a snug friction fit — the pocket grips the base walls. If the fit is very tight, press down evenly on the base edges, not on the model. Once seated, the top surfaces sit flush. Works with both plain and slotted 25mm bases.

Flip the converter over and push the base out through the underside opening from below. You never need to grip the model — protecting paintwork, fragile weapons, banners, and anything else that would break if you tried to pry the model out. The underside opening is deliberately smaller than the pocket so the base can't fall through during play.

The converter texture matches OBS bases, so a single colour across the rim and bevel gives a seamless look. Paint the converter rim to match your base rim and it disappears visually — especially effective in ranked formations where consistency matters. If your existing bases have scenic rims, match the converter rim to the same scheme.

The outer bottom width is exactly 30mm — converted bases sit tight in formation with no gaps. Keep texture off the converter bevel edges for clean ranks, same as you would with a standard base. A uniform rim colour across converted and non-converted models ties the army together on the table.

The friction fit plus the retention lip means the base is secure for gaming without adhesive. If you want permanent, a thin line of superglue around the inner pocket before inserting makes it solid. Most hobbyists leave them friction-fit so they can switch back if base sizing changes again — that flexibility is the whole point of a converter.