Guarantees

We provide warranties on certain of our products at the time of sale. The standard warranty period for our capital and reusable equipment is generally one year. Liability under service and warranty policies is based upon a review of historical warranty and service claim experience. Adjustments are made to accruals as claim data and historical experience warrant.

Changes in the carrying amount of service and product warranties for the nine months ended September 30, are as follows:



	2010			2011

Balance as of January 1,	$	3,383		$	3,363

Provision for warranties	2,478			3,537

Claims made	(2,556		)	(3,273		)

Balance as of September 30,	$	3,305		$	3,627