These are heatsinks for the Samsung LED QB288 style boards, or any other boards you may want to use them for. They are black and measure approximately 206mmx310mm. But, if you know anything about these boards, you know you can use a bigger or smaller board on any heatsink.
If wanting to use screws to mount your board to heatsink, you may have to drill holes and use self tapping screws. The item "4 x Heatsink for QB288 LED Quantum Samsung lm301b lm561C Sun Board Grow Light" is in sale since Thursday, May 2, 2019. This item is in the category "Home & Garden\Yard, Garden & Outdoor Living\Hydroponics & Seed Starting\Grow Light Kits".
The seller is "ucandewit" and is located in Erwin, Tennessee. This item can be shipped to United States, Canada, United Kingdom, Denmark, Romania, Slovakia, Bulgaria, Czech republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Australia, Greece, Portugal, Cyprus, Slovenia, Japan, China, Sweden, South Korea, Indonesia, Taiwan, South africa, Thailand, Belgium, France, Hong Kong, Ireland, Netherlands, Poland, Spain, Italy, Germany, Austria, Bahamas, Israel, Mexico, New Zealand, Philippines, Singapore, Switzerland, Norway, Saudi arabia, Ukraine, United arab emirates, Qatar, Kuwait, Bahrain, Croatia, Malaysia, Brazil, Chile, Colombia, Costa rica, Dominican republic, Panama, Trinidad and tobago, Guatemala, Honduras, Jamaica, Aruba, Ecuador, Guadeloupe, Iceland, Luxembourg, Maldives, Oman, Peru, Pakistan, Paraguay, Reunion, Viet nam, Uruguay.