(11) Concentrations of Credit Risk, Significant Customers and Geographic Information - Significant custmers as a percentage (Details)	12 Months Ended
Dec. 26, 2020	Dec. 28, 2019
Significant Customer Percent of Revenue
A	36.00%	43.00%
B	21.00%	14.00%
C	16.00%	13.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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