Ruff Land Single Door Dog Kennel - Designed by outdoorsmen, endorsed by celebrities, this dog kennel sets the standard for built-to-last dog kennels. Vent hole pattern displayed in each photo comes standard kennel (1 3/8in hole size), with two finger holes in the back. This dog kennel can be stacked and customized with the add-on options. Ruff FLEX Technology StackRight Design SureVent Tapered Wall Design UpSide Raised Floor Interior 2-Way Door No Bite Grid Pattern Design Rattle-Free 2nd Generation Models