Oct 28, 2020 · The complete specifications of the SPEAR are shown on Fig. 2. Fig. 2. Kromek SPEAR specifications adapted from the original PDF. Kromek offers a turn-key USB gamma spectrometer GR1 CZT, which is is very similar to SPEAR, except for the larger 10 x 10 x 10 mm 2 crystal size and USB connectivity. Unfortunately, high cost of GR1 (approximately $16,000) places this instrument out of reach of the vast majority of nuclear science enthusiasts.