Vessberg, pl. 58, no. 110, Hayes, no. 146, Constable-Maxwell Collection, lot 125, and Stern, nos. 37, 38 and 103 all belong to Isings Form 70, and all have similar bodies to this flask. However, the rims of all of these vessels are folded downwards, whereas the fold in the rim of this flask creates a ridge. The dating of this vessel is based on the dates of the examples above and Isings’ remarks on the form. This stylistic variation is slight enough that this flask could easily have been made in the same area as any of the examples cited. The rim of Davidson, no. 796, which dates to the fifteenth century C.E. or later, is also comparable. - Ancient Glass in the University of Colorado Museum