Vest extenders for sainsburys vests

[Spotsondots]

Does anyone know where I might be able to get vest extenders that are compatible with sainsburys vests? We have some but they don't seem to work with our sainsburys vests... Thanks!

I just assumed that all vest extenders fit all vests...but just tried one of ours on a Tu vest, and they definitely don't fit. The poppers on the vests are slightly smaller than normal.
Hope you manage to find some soon!