What the 26 V standoff and 42.1 V clamp mean for your board
The SMAJ26A-13 is a unidirectional Zener-type TVS diode in a DO-214AC (SMA) package. Its 26 V reverse standoff voltage means it sits across a 24 V rail and stays invisible until a transient pushes the line above that threshold — it does not conduct during normal operation. When a surge hits, the diode clamps at 42.1 V maximum and shunts up to 9.5 A of peak pulse current in the standard 10/1000 µs waveform.
Package and hand-solderability
The DO-214AC (SMA) footprint is one of the friendlier SMD packages for hand assembly — the two-terminal body is large enough to tack with a fine-tip iron, and the cathode band is clearly marked.