Panasonic PT-RZ21K Operating Instructions Manual page 250

Chapter 7 Appendix — Precautions for attaching the Ceiling Mount Bracket
r Specification for the screw holes to fix the projector (projector bottom view)
Unit: mm
250 - ENGLISH
110 (4-11/32") 145 (5-23/32")
110 (4-11/32")
135 (5-5/16") 145 (5-23/32")