We have replaced the version of ULTRA (ZS-405) with the ULTRA Plus ZS-406. ULTRA Plus maintain the same look as the current version of ULTRA and is compatible with the current version of ULTRA's software, so users can easily migrate to the ULTRA Plus. A brief overview of their differences: Batteries: ZS-405 3000mAh ZS-406 5000mAh Normal mode: ZS-405 100k-800MHz ZS-406 100k-900MHz ULTRA mode: ZS-405 800MHz-5.3GHz ZS-406 900MHz-5.4GHz Color: black Material: ABS Package Contents: 1 set x Handheld Spectrum Analyzer Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.