Heywood Wakefield Orange Fiberglass and Chrome Stacking Chair

I found 4 of these at an estate sale. I cannot find this exact chair anywhere in my searches. They are orange fiberglass and chrome Heywood Wakefield stacking chairs.
There are some numbers on the bottom. SH1257 and 17825.Can any of my mid-century friends tell me anymore about these great looking chairs? Thanks so much for any help.