4. ACCOUNTS RECEIVABLE
Accounts receivable are shown in the accompanying consolidated balance sheet net of an allowance for doubtful accounts of less than $0.1 million as of both December 31, 2011 and 2010. The Company performs ongoing credit evaluations of its customers and adjusts credit limits based upon payment history and customers' creditworthiness, as determined by the Company's review of their current credit information. The Company continuously monitors collections and payments from its customers and maintains an allowance for estimated credit losses based upon its historical experience and specific customer collection issues that the Company has identified. Accounts receivable are evaluated and written-off against the allowance if they are determined to be uncollectible.