So called “RS-SG” (sanwa catalog ref) , relabeled Sanwa switches for OBSF-30RG & OBSF-40RG buttons are really OMRON B2R-G1 reed switches (“G1” printed on the case), if anyone is interested .
Apparently the Seimitsu discontinued buttons with the same omron switch were PS14-GX , and PS-14GXN (both opaque and clear cap covered plunger). They’ve been discussed here before on SRK.
according to a japanese site, the specs are the following :
-actuation distance : 1.57mm
-bottom out : 2.64mm
-force needed to depress the plunger : >= 35.3gf
-actuation force : 50gf
-for to bottom out: 61gf
used in HORI RAP SE before.
source: パーツデータ - 家庭用アーケードスティックWiki - atwiki（アットウィキ）
B2R-G1 switch parts :
source: ベラボースイッチ特集2（ベラボースイッチ製作） - コントローラ研究室
edit: Sanwa also made OBSL-30RG, screw-in 30mm buttons, in 6 opaque color variations (including black) . Pic links on SRK are dead so here it is:
OBSL-30RG had unusual bodies for screw-in buttons at the time as the threaded part extended lower around the reed switch in order to accomodate to extra thick control panels ( e.g. wood ) unlike the normal sized threaded part on the OBSN-30RG screw-in, also discontinued , and which also sported the same Omron reed switch.
OBSN-30RG screw-in 30mm buttons :
There were also NAMCO 28mm buttons with an Omron B2R-G1 switch, there’s an article in Erwin’s blog showing a comparison with Sanwa OBSF-30RG and Seimitsu PS-14-GX :
