Inventories (Details) (USD $) In Thousands, unless otherwise specified	Mar. 30, 2013	Dec. 29, 2012
Summary of inventories
Raw materials	$ 5,623	$ 5,564
Work in process	3,746	3,695
Finished goods	3,826	3,980
Provision for slow moving inventory	(685)	(680)
Total	$ 12,510	$ 12,559