| In millions, except per share items | Dec-31-20 | Dec-31-19 |
| | S-1 | S-1 |
| Cash flows from operating activities: | | |
| Net loss | -30.4 | -11.5 |
| Adjustments to reconcile net loss to net cash used in operating activities: | | |
| Stock-based compensation expense | 0.3 | 0.2 |
| Change in fair value of common stock warrant liabilities | 1.3 | 0.3 |
| Changes in operating assets and liabilities: | | |
| Prepaid expenses and other assets | -0.1 | -0.5 |
| Accounts payable | -0.2 | 0.5 |
| Accrued and other current liabilities | | |
| Accrued product warranties | | |
| Deferred revenue | | |
| Operating lease liabilities | | |
| Net cash used in operating activities | -16.6 | -6.7 |
| |
| Cash flows from investing activities: | | |
| Purchases of property and equipment | -0.5 | -0.9 |
| Net cash provided by (used in) investing activities | -0.5 | -0.9 |
| |
| Cash flows from financing activities: | | |
| Payments on notes payable | -0.2 | -0.3 |
| Proceeds from stock options exercised | 0.0 | 0.0 |
| Net cash used in financing activities | 4.7 | 22.3 |
| |
| Supplemental disclosures of cash flow information: | | |
| Non-cash investing and financing transactions: | | |
| Cash and cash equivalents | | |
| Restricted cash, current | | |
| Restricted cash, non-current | | |