Dinosaur Birthday Party Pack - 12 Invitations, 12 Thank You Cards, 24 Envelopes T-Rex Dinosaur Birthday Party Pack includes 12 Invitations, 12 Thank You Cards, 24 Envelopes Size is 4 x 6 Inches. Full color designs on both front and back of invites and thank you notes. Flat (non-folding) cardstock design for both invites and thank you notes. Heavy-weight cardstock with uncoated finish for easy writing. Invites are fill in the blank style: For, Date, Time, Place, RSVP Thank You cards are easy fill in the blank style for kids.