From Amazon
Clairefontaine - Ref 96008C - Pastelmat Pastel Card Pad No.2 (12 Sheets) - 360gsm Card - 30 x 40cm - Assorted Colours - Specially Formulated For Use With Pastels
Viking Direct
Clairefontaine Pads 96008c 360 gsm 30 x 40 cm Multicolour 12 Sheets