get one if your on price for more money or day work to make your life easier...
recent example..... same job with and without a wrench..... 2 days with and 2 & half days without ....that's 25% more money .... pays for itself in a week if your on the right job ...
Also invest in some ear defenders aswell we don't use them but another firm was doing a job across the road from us yesterday n my head still ringing now! Normally just from the gob shites at work but them drills were noisy like!