This excerpt taken from the SKIL 10-K filed Apr 13, 2007.
(k) Fair Value of Financial Instruments
Financial instruments consist mainly of cash and cash equivalents, investments, restricted cash and accounts receivable. The Company determines fair value for short-term and long-term investments based on quoted market values. The carrying amounts of accounts receivable is net of an allowance for doubtful accounts, which is based on historical collections and known credit risks.