variations in the material cost / adjustments made to change in the material cost
Explanation:
If I may venture to translate all the phrase, I daresay it goes like this:
(subject to variations in the material cost/subject to adjustments made to change in the material cost).
According to what it says here, I think the applicable price may fluctuate in response to variations or adjustments in the material cost, which goes down in this situation depending on decrease in such cost. I deliberately avoid using such big words as “indexation, index adjustment, indexed to …, sliding scale, sliding scale plan/system, etc.” to render the “スラ＝スライド” into English.
|  Katsushi Saito
Local time: 09:16
Native speaker of:  Japanese
PRO pts in category: 12
|
|
The translation workplace 
peer agreement (net): +3
