OBSF-24

1. Overview

The Sanwa Denshi OBSF-24 is a 24mm snap-in arcade pushbutton introduced in 1984, the industry standard for Start, Select, and auxiliary button positions in Japanese cabinets and fightsticks. It is the smaller sibling of the OBSF-30 (main action buttons); Sanwa's official site states "Start and Select buttons use OBSF-24 or OBSN-24; main buttons are OBSF-30." It integrates a Sanwa SW-68 non-clicking microswitch, slightly convex plunger, and snap-in mount for 2–3.7mm panels (28mm outer diameter). The rise of hitbox/leverless controllers has made it the primary button for entire panels — a typical Hitbox uses 11 OBSF-24 and only 1 OBSF-30.

2. User Sentiment

The FGC consistently treats the OBSF-24 as the definitive 24mm button. Focus Attack customers rate it 5/5 (Black has 10 reviews), with one calling it "the gold standard for fight sticks." r/fightsticks: OBSF-24 vs OBSF-30 is purely a size distinction — both share the same SW-68 switch. The Shoryuken/Slagcoin community rates it "very light" tension and "very high" smoothness. The Chinese SF6 community calls it "街机界黄金标准" (arcade industry gold standard). The main 24mm competitor is the Seimitsu PS-14-DN (snap-in) / PS-14-DN-K (screw-in): Seimitsu is slightly firmer and less sensitive, preferred by some leverless builders to avoid accidental presses during hand rest. Historically, Sanwa did not commercially produce black OBSF-24 — Hori held a 10,000-unit limited run (2009), driving some modders to Seimitsu. Dark Hai color was HRAP2 SA-exclusive and sold secondhand for $5 each.

3. Real-World Applications

Standard for Start/Select/Home/Turbo/Coin on MadCatz TE, Qanba, and Hori HRAP fightsticks; fills the Start button in Sega Blast City, Versus City, and Taito Astro City cabinets. In leverless all-button controllers (FightBox RAC-J800B, ALRAYA F1, Smash Box), 11 OBSF-24 + 1 OBSF-30 is the dominant layout. The Smash Box (Super Smash Bros.) uses OBSF-24 exclusively and was tournament-approved at EVO 2018 and GENESIS 4. Also deployed in MAME/Arcade1UP home cabinets, Raspberry Pi builds, guitar kill-switch use, and niche retro console controller builds (Atari Jaguar, ColecoVision).

4. Technical Specifications

• Type: 24mm snap-in momentary pushbutton, non-latching, non-clicking
• Mounting hole: Φ24 ± 0.1mm; overall diameter 28mm
• Panel thickness: 2–3.7mm official max (community reports up to 5mm functional)
• Switch: Sanwa SW-68, 2.8mm / 0.110in QD spade terminals
• Feel: Very light tension, very high smoothness, very short engage distance (slagcoin.com chart)
• Colors: 14+ solid colors; two-tone variants (K/DH, K/B, K/Y, K/O, etc.); metallic OBSJ-24
• Variants: OBSF-24KK (square plunger); A-OBSF-24-K / OBSF-24F-CAU-X (internal CAU one-touch connector, not QD-swappable)

5. Ordering & Compatibility

Pricing: $2.40–$2.75 USD (Focus Attack, Paradise Arcade, Arcade Renovations, Arcade Shock at $2.45), €2.50 (SmallCab, Arcade Express, JammaStar), ¥245 (akecon.games Japan), A$3.50 (OzStick AU) — ~$0.50 less per button than the OBSF-30. Individual rims (for color-swapping) are $1.25 at Paradise Arcade; Mix & Match 24mm plungers in 9 colors at Focus Attack. Drop-in compatible with MadCatz, Qanba, Hori, Razer fightstick Start/Select holes using 2.8mm QDs. Dark Hai (NOS) and Grey Violet are ArcadeShock-exclusive. The A-OBSF-24-K one-touch variant is not interchangeable with the standard QD model.

6. Known Issues

Snap-in clips are designed for metal panels up to 3.7–4mm; in thicker wood or acrylic the clips may not fully seat, though most builders report acceptable retention. The A-OBSF-24-K (CAU connector) variant is externally identical to the standard button but electrically incompatible. High-concentration alcohol or solvent cleaners damage the resin plunger — Sanwa's manual specifies neutral detergent only.