Multilevel strings of geophone tools are changing the economics of well seismic because rig downtime is divided by almost the number of levels while data quality is considerably improved. Since the introduction of well seismic methods, check shots, vertical seismic profiles, and walkaway VSPs, the cost of rig downtime has been a major consideration. It has limited the use of well seismic, particularly offshore. Multilevel geophone tools were initially developed with the reduction of rig downtime in mind. Single level tools are now starting to be replaced by strings of tools. Putting tools on a string offered an opportunity to improve their mechanical characteristics. Some of these improvements resulted from design, while others were due simply to the fact that a string of tools operates simultaneously at more than one level.