The RET-X-ISO probes have all the same features of the RET-X series plus: * an isolated sensor （can be used with montoring equipment where electrical interference from other electrodes may be present）. * Reinforced strain relief for applications where probe is in more frequent use. Smooth ball tip. Stainless steel shaft - 1" long, .059" dia. Tip diameter .125". 5 foot lead length. Time constant 0.8 secs. The new RET-3-ISO for mice and neonatal rats has all the same features of the RET-3 plus: * an isolated sensor （can be used with montoring equipment where electrical interference from other electrodes may be present）. * Reinforced strain relief for applications where probe is in more frequent use. * Smooth ball tip. Stainless steel - 3/4" long, .028" dia. Tip diameter .065". 5 foot lead length. Time constant 0.5 secs.