Checkline K-400 [K-400-A] Analog Thickness Gauge, Range  0 - 30 mm, Depth Of Jaw 400 mm, Feeler A For Rubber, Felt, Soft Materials, Non Wovens, Metric Units. Measuring Range: 0 - 30 mm / 0 - 1.00 inch, Resolution: 0.005 inch / 0.1 mm, Jaw Depth: 400 mm / 15.75 inch. The Checkline K-400 analog dial thickness gauge features an easy to read analog display along with the high accuracy. The K-400 model is available with 5 different feelers, which can be found below. Measurement is done by a spring force. Opening by lifting device (lever) - self closing.