Overview of Delmhorst 26-ES Electrode Hammer Probe:

The Delmhorst 26-ES hammer probe for measurement of hardwood ships with 2 insulated 1 1/8" penetration pins installed.  This is the most popular Delmhorst hammer probe, and can be purchased for a package price with many meters. When ordered as part of a package, it comes with an upgraded case to hold both the meter and probe, the package of spare parts listed below, and an additional package of 10 spare pins matching the ones installed when it ships (1 1/8" penetration, insulated).

When purchased alone, it includes a package of spares, including replacement washers, 1/2" penetration insulated pins, one set of spares of the installed pins, and a pair of 1/2" penetration UNinsulated pins. 

Used to measure moisture in hardwood, paired with any suitable Delmhorst meter (see suggestions under Related Products). 

This electrode is also available as the 26-ED, which includes a depth gauge to measure pin penetration depth.

Delmhorst also offers a second hammer probe, the 18-ES, for deeper penetration into timber.  This hammer probe is also available with a depth gauge, as the 18-ED.