GST 5% certificate issued by DSIR

Harish Chand Saini (226 Points)

11 April 2019  
sir,

we are manufacturer and registered in GST. GST @ 18% on our products.

our customer has provided us a certificate issued by dsir on dt August 2016 valid till 2021 for purchase GST @ 5%.
Is this certificate is valid in GST regime?
Can we sold the material @ 5% by old certificate or required any other certificate.