A18 Petcock

A18. 12x1 female spigot right

A18 12×1 spigot right
01z2391037  $19
↑res ←off  on↓
made in Italy by OMG

A18b 12×1 spig. right
5322-A  none
←res  on↓ off→
Italy-made Franconi

Links to photos of examples:
1976 Flandria Bermuda Hampton (cover hole widened)
1977 Flandria Bermuda Hampton (no cover no petcock)
1978 Flandria Bermuda Pembroke
1978 Vespa Bravo original
1978 Vespa Bravo gas tank original
1978 Cimatti City Bike (when 10-12 adaptor is there)
1978 JC Penney Pinto (no petcock)
1979 Columbia 2220 (sheet frame) original
1979 Columbia 2220 (sheet frame) with spigot down
1979 Batavus Starflite with spigot right
1982 Batavus Mondial with spigot right
1980 Columbia Medallion (top tank) original
1981 Murray 8320 original
Tomos 233727 gas valve original
2007 Tomos Sprint with 233727
1980 Sachs Prima original
1969 Honda PC50

Columbia sheet frame: The sheet metal frame Columbia is different from a tube frame Columbia. It can have different marketing names. Original valve was spigot right, but down, back, or left also fit.

Tomos A55: All Tomos models with the A55 engine have a 12×1 spigot right gas valve #233727, above the left side of the engine. Earlier A35 models had a opposite valve on the opposite side. 

Vespa Bravo: This screw-on valve is for Vespa Bravos with a metal tank. Some have a plastic gas tank, with a different gas valve than this. See clamp-on valves below.

Flandria Bermuda: Bermuda (made by Flandria) mopeds use this vertical 12×1 spigot right valve, but in the horizontal position. There is no reserve function. The owners manual says that either rear or forward is closed (off), and outward is open (on). The valve handle is protected behind the cover. There is a finger width long slot in the right cover, for one-finger access.