1 INTRODUCTION

2 OBSERVATIONS AND DATA REDUCTION
2.1 X-ray observations
2.2 Radio observations
2.3 Optical observations

3 IDENTIFYING SYSTEMS WITH CAVITIES

4 CAVITY ENERGETICS

5 CAVITY AGES

6 COOL CORES
6.1 Clusters in the MACS sample with cavities
6.2 MACS cluster sample

7 CAVITY SCALING RELATIONS

8 RESULTS
8.1 Clusters with "clear" cavities
8.2 Clusters with "potential" cavities

9 DISCUSSION
9.1 Selection effects
9.2 Detection rates
9.3 Cavity properties
9.4 Evolution of cavity properties

10 CONCLUDING REMARKS