They were often strung in long strings, too, for use on high voltage pylons.
Lapp is in LeRoy, New York and is still operating there today. Collectors call this distinctive glaze color "pumpkin" and it's often used to identify unmarked Lapp products. A date would probably have been just under the Lapp logo and it's impossible to guess the age without it because this type was made from the 1920s up through the 1960s when the glaze colors changed.