Limited time deal. Amazon has the well-reviewed Yes4All 2-Pack 10lbs each 20lbs Attachable Rucking Weight for Backpack for $34.62 with free shipping on $35+ or with Prime.

Also check out:

• Yes4All Wrist and Forearm Blaster for $8.52
• Set of 4 Yes4All Standard 1" Cast Iron Weight Plates for $15