| In millions, except per share items | Dec-31-19 | Sep-27-19 | Jun-28-19 | Mar-29-19 | Dec-31-18 | Sep-28-18 | Jun-29-18 | Mar-30-18 |
| | 10-K | 10-Q | 10-Q | 10-Q | 10-K | 10-Q | 10-Q | 10-Q |
| Sales | 27.7 | 29.4 | 35.9 | 36.8 | 37.2 | 36.3 | 32.2 | 30.0 |
| Sales growth | -25.5% | -19.0% | 11.6% | 22.4% | 21.9% | 12.4% | -6.9% | -9.2% |
| Cost of sales | -18.4 | -19.2 | -22.6 | -23.7 | -23.7 | -18.2 | -10.7 | -5.0 |
| Gross profit | 9.4 | 10.3 | 13.3 | 13.0 | 13.4 | 13.3 | 11.8 | 10.9 |
| Gross margin | 33.8% | 34.9% | 37.0% | 35.5% | 36.1% | 36.7% | 36.6% | 36.2% |
| |
| Operating expenses: | | | | | | | | |
| Selling, general and administrative | 7.5 | 7.2 | 7.2 | 6.7 | 6.7 | 6.6 | 6.4 | 6.2 |
| Research and development | 3.2 | 3.2 | 3.1 | 3.0 | 2.9 | 2.8 | 3.0 | 3.0 |
| |
| Pension | | | | | | | | |
| Total operating expenses | 10.8 | 10.6 | 10.5 | 10.0 | 9.8 | 9.7 | 9.6 | 9.4 |
| Operating income (loss) | -1.5 | -0.4 | 2.7 | 3.1 | 3.7 | 3.7 | 2.2 | 1.5 |
| Operating margin | -5.3% | -1.2% | 7.6% | 8.3% | 9.8% | 10.1% | 6.8% | 4.9% |
| Other income, net | -0.3 | | | | -0.3 | | | |
| Income (loss) before income tax provision | -1.7 | -0.6 | 2.4 | 2.7 | 3.3 | 3.3 | 1.8 | 1.1 |
| Income tax benefit (provision) | 0.1 | | 0.0 | | 0.0 | 0.1 | 0.1 | 0.1 |
| Tax rate | 7.9% | 3.3% | 0.4% | 0.4% | | -2.0% | -5.4% | |
| Net income (loss) | -1.6 | -0.6 | 2.4 | 2.7 | 3.3 | 3.4 | 1.9 | 1.2 |
| |
| Net income (loss) per common share - basic | ($0.14) | ($0.06) | $0.21 | $0.23 | $0.28 | $0.29 | $0.16 | $0.10 |
| Net income (loss) per common share - diluted | ($0.14) | ($0.05) | $0.21 | $0.23 | $0.28 | $0.28 | $0.15 | $0.09 |
| |
| Weighted average common shares outstanding - basic | 11.5 | 11.4 | 11.4 | 11.4 | 11.4 | 11.4 | 11.4 | 11.4 |
| Weighted average common shares outstanding - diluted | 11.6 | 11.7 | 11.8 | 11.9 | 11.9 | 11.9 | 11.8 | 11.7 |
| |
| Comprehensive income (loss), net of tax: | | | | | | | | |
| Net income (loss) | -1.6 | -0.6 | 2.4 | 2.7 | 3.3 | 3.4 | 1.9 | 1.2 |
| |
| Decrease (increase) in minimum pension liability | | | | | | | | |
| Total comprehensive income (loss) | | | | | | | | |