BBWSG-19 Replacement Glass. Is only made to fit that model BBWSG-19 brass inset cup. The replacement glass includes 1 oring  ( Oring included must be used with glass )

To install use provided oring and install on the brass BBWSG-19 Diffuser housing. Moisten the inside of the Glass cup and around the oring and gently push in. Be careful and do not force the Brass housing. If its difficult use more moisture .