The first so-called “smart gun” has hit the shelves at U.S. retail outlets, including one of the biggest firearms stores in California, according to the Washington Post.

The Smart System iP1, a .22-caliber pistol made by the German gun-maker Armatix GmbH, can only function with an accompanying wristwatch, which is sold separately.

When the RFID-equipped watch is activated by a PIN number and placed near the gun — like when a shooter grips the handle — it sends a signal to unlock the gun and a light on the back of the weapon turns green, according to the report. Otherwise, the firearm stays locked and the light on the back remains red, it stated.

The pistol sells for $1,399 and the watch retails for another $399 — more than double the cost of .40-caliber Glock handgun, according to the article.

The company is betting that demand for the technology will increase as consumers seek guns modified for safety.