The squares are 1/2in or 1.3mm in size.
ORAJET 3651 is a 2.75 mil thick, white gloss vinyl. It has a solvent based, permanent grey adhesive. This vinyl is ideal for general signage and other medium-term, flat, indoor and outdoor applications.
ORAJET 3621 is a 3 mil thick, white gloss vinyl. It has a water based, removable grey adhesive. This vinyl is ideal for general signage and other short to medium-term, flat, indoor and outdoor applications.