Hugh Hefner shows off wedding invitations

(CBS) Invitations are being sent out for Hugh Hefner's wedding to girlfriend Crystal Harris - and if you're not expecting one in your mailbox, you can check them out on Twitter.

The Playboy founder posted an image of the invite to the couple's June 18 nuptials, writing, "Friends and family are already receiving our wedding invitation."

Pictures: Crystal Harris
Pictures: Celebrity weddings and engagements

The envelope features a stamp with the bride and groom, while the invitation, written in black ink and scattered with pink rhinestones, reads:

"Crystal Harris and Hugh M. Hefner request the pleasure of your company at the celebration of their marriage."

The ceremony will take place at 6 p.m. at the Playboy mansion. Reception and dinner will follow, according to the invite, and semiformal attire is requested.

Hefner, 85, and Harris, 25, announced their engagement in December. It will be the Playboy founder's third marriage.