retention material是什么意思?

Served as lead project manager in the development and implementation of approximately 250 projects annually, consisting of marketing collateral, direct mail, direct response television, retention materials, business-to-business communications and Spanish language collateral

作为项目经理，每年负责大约250个项目的管理和实施，包括相关营销、直邮、电视广告营销、后面的不知道怎么翻译了。
请高手指教~！
谢谢！

retention material是什么意思? visa卡 Mater卡 招商银行 外贸中retention和detention的区别 What’s the mater? 什么意思？谢谢 whatever 与 no mater water的区别 mater文件不能运行的问题 "retention arrangement"的中文准确译名是什么？ 求一首英文歌no mater what I do,I'm crazy over you（歌词） The headmaster came up to see (what was the mater)(what the matterwas)哪个对 求一首经典英文歌．男的唱的．歌词前四句的前两个词都是no mater