Can anyone identify this part?

[acai]

It broke off the faucet lever handle and now it's loose and won't shut off the water properly.

Tried Lowe's and Home Depot but they have no clue.

 

[Caduceus]

That looks like the little plastic insert to the handle that holds it tightly to the splines on the cartridge stem splines. By posting a picture of the faucet and cartridges and identifying the manufacturer, you may be able to order a new handle or part.

 

[Zeppelin5000]

What kind of faucet?

 

[acai]

Could this be it????

http://www.ebay.com/itm/Kohler-Gp-1074231-Spline-Adaptor-Kit-Genuine-Parts-/221602142640?pt=LH_DefaultDomain_0&hash=item33988459b0

 

[Caduceus]

Could be. Might cost ya $5 to find out for sure.