Great Material: These replacement primer bulbs are made of plastic, which is reliable, sturdy, not easy to break, wear resistant and practical. Compatibility: Primer bulbs are compatible with for Walbro 188-512, WT-23A small engines, for Poulan echo chainsaws, for Ryobi BP42 Homelite Bolens lawn mowers and leaf blowers 125B 125BX 125BVX 530047721 503936601. Please note that our product isn't sponsored or endorsed by the brand it fits, including for Walbro, for Poulan and for Ryobi. Widely Used: Our primer bulbs for small engines are great for lawn mowers, blowers, trimmers, chain saws, trimmer carburetors, etc. Suitable Size: Replacement primer bulb is measured about 2.2x2.2x3.46cm/0.86x0.86x1.36 inch. Please check this size carefully before ordering. Colour:As Shown Material:plastic Package Contents: 2 x Replacement Primer Bulbs Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.