Union 2” ST4 Replacement Iron for other makes No.4 and No.5These 3⁄32” thick replacement irons are made from the same highly consistent American O1 tool steel with military spec heat treatment as the thicker irons for Union planes. At 'just a bit' thicker than most makes standard irons, they will nonetheless fit straight in to almost all makes of iron bench plane including Stanley, Record, Millers Falls, Woden, WS, Preston etc.One nice feature of Union plane irons is that the hole at the end of the slot is at the top, as it is on old British planes, so installing and removing the cap iron all happens away from the edge and it is then slid into place.The faces of the ST4 irons are Blanchard ground which leaves a distinctive curved crisscross pattern on the face of the tool.
Standard 2” width 3⁄32” thickness AISI O1 RC61
